In 2007 I created a WordPress plugin to add some features to one of my sites, and threw it up on my blog as a free download for anyone else that could make use of it.<p>There were so many downloads, comments, feature and support requests I couldn't keep up. I started from scratch and created a premium version that did more and was better designed, front-end and back, and tossed a link to that on my blog as well.<p>I sold about $200,000 in licenses to that plugin before selling the rights to it for another $90,000 1.5 years later.
I wrote a payment system called 'webpay', and sold individual licenses. One day some guy calls up and asks about a source license. I didn't feel like selling so I asked an outrageous price, $100,000, and jokingly I added 'in small bills'. Three days later (Christmas eve, no less) some guy shows up at my house with a suitcase full of fifties... he'd been on 3 flights from Minot, North Dakota with a bunch of lay-overs. We waited for the banks to open so the money could be deposited and I burned him a CD.
I have blogged for the last four years. Apparently some of what I wrote was interesting enough that people remember my name. Some of them have large amounts of other people's money to spend on outside consultants. This is a fortuitous and totally unplanned coincidence.
Back in 1995, I started dabbling with the web design in my final year of engineering. Back then, the web was a brand new world and I was having a lot of fun trying out new thing - as my first project, I created a fan site for the Calvin and Hobbes comic strip (Cool Calvin & Hobbes Collection - <a href="http://www.nivmedia.com/calvin" rel="nofollow">http://www.nivmedia.com/calvin</a>).<p>After a few years, I moved state, degrees, jobs and stopped maintaining it. In 2005 I happened to check the web logs and noticed that it was still getting several hits a day. In a fit of nostalgia, I redesigned the whole site using the knowledge I had gained in the past decade (web design was always a hobby, not a job), and in the process added some Amazon links and some Google adverts.<p>I've barely touched the site since 2006, but it still consistently gets several hits every day and generates around $1-1.5k in Google ad revenue and $400 in Amazon revenue a year.<p>Nothing to retire on - but as the first site I ever created and for something I don't maintain, it still brings a smile to my face when the ad revenue arrives in my bank account :)
I wrote about <a href="http://PeterAnswers.com" rel="nofollow">http://PeterAnswers.com</a> on my blog and it became the #1 google result for "ask peter". The post got a ton of traffic and I built a clone called <a href="http://askjud.com" rel="nofollow">http://askjud.com</a><p>-- Redirected everyone, added Adsense, and now it gets 6k - 10K visits / day.
Remember the feature of the old iPods where you could add notes that used a subset of HTML? When I was in high school I wrote a little command-line program that would generate a bunch of notes linking to each other that in effect let you play blackjack on your iPod. It was a total hack, but I had a casino contact me asking to sponsor it. It didn't end up happening, but it's the closest I've come to accidentally making money.<p>I've written other open-source software since and had people offer money for new features, but I'm not sure that counts since it involves additional work.
In Fall 08, I wanted an iPhone app to track up-to-date poll results between Obama and McCain and...as it turned out, there wasn't an app for that. So I wrote one in a week and sold ~50,000 copies (<a href="http://structlab.com/iphone/polltracker/" rel="nofollow">http://structlab.com/iphone/polltracker/</a>)
A few years ago I started helping out making user generated content for a HL2 mod in my spare time.<p>The mod got quite popular and a couple of us got invited on an all expenses trip to the US to visit Valve's HQ and meet Gabe etc along with the mod's creator.<p>Helped re-write the entire thing from scratch to eliminate the myriad of bugs which had gradually crept into each subsequent update, still in my spare time.<p>A few months later started selling the mod on Steam.
I think so far it's sold in excess of 500k copies.<p>In case you haven't guessed, the game was Garry's mod.<p>I didn't make anywhere near as much as Garry the mods original author, who's pretty much set up his own fully funded game dev studio with the proceeds, but it was a fun summer nonetheless.
In 2007 I had been working as a network engineer for a big networking vendor for 6 years, making close to 6 figures. I had also been preparing for 6 months to pass a very hard networking certification (CCIE), when my boss decided that he could hire a cheaper engineer and fired me. I had no idea what to do next but I had lots of free time on my hands. So, when my gf, who was into handmade crafts, asked me to set up a wordpress blog for her, I immediately decided to help her (even though I knew nothing of HTML or web development) because my self-confidence was going down in a spiral to the ground.<p>The blog made $500 in the first month from Adsense. A year later, close to $1000 a month. I created a few more websites around the same concept and now I make close to $2500 a month in passive income, which allowed me to spend a year studying Python full time (and web development in general) and also lets me work full time on my startup. I'm not rich, but I make my own time, work on my own projects and it's a nice sum of money for someone living in Brazil.
Juggling.<p>I juggle as a hobby, and someone invited me to give a talk about the structures and theory behind it. I make a lot of money giving that talk multiple times every year.<p>For the last 25 years - about 1800 talks.
I wrote 10MinuteMail.com in order to teach myself the JBoss Seam framework. I hadn't looked to see if there were other sites doing the same thing (there were), with more features (there were), etc... and never intended to make any money with it. It got pretty popular and I make a bit on Google Ads. Not enough to retire on or anything, but it makes low five figures annually.
<a href="http://www.ThatHigh.com" rel="nofollow">http://www.ThatHigh.com</a> - started in college as a bit of a joke and now pays my rent in downtown San Francisco.
Earlier this year somebody contacted me about selling a domain name called "timemanagementclass.com". It was vaguely related to some other projects we were doing and we thought it might be useful.<p>I negotiated hard with the seller and got him down to $200.<p>Then a week later somebody else called and said he'd wanted the domain and was too late in responding to the original seller. He WAS really in the time management space and really wanted the domain. So I sold it to him for $900.<p>There's a moral to this story:<p>1. Always negotiate hard and be willing to walk away if you don't get what you want. This takes a lot of emotion out of the process.<p>2. Don't dither around like the other buyer did. He was part of a large organization and to actually sell him the domain took almost 6 weeks.
I wrote a small Facebook application that let friends send me text messages from my facebook page for free (using email=>sms that my provider offers). 0 => 3,000,000 users in a couple of weeks.
I started blogging for enjoyment long before the word entered the popular lexicon. That never made a ton of money directly (though it did make some) but it did indirectly help me land a book deal and start a couple related businesses that made a lot of money.<p>It also gave me a chance to figure out how to write and communicate well, which I think is why we got into Y Combinator. I'd say that writing is probably the second most valuable life skill (behind understanding the concept of expected value) that I've picked up to date, and I was abysmal at it before I started that first Movable Type blog.<p>So in a roundabout way, blogging has made me a fortune, though I never could have anticipated it. When I started nobody had made much off of it.
I hacked a Linux driver to make a slightly obscure hardware device work in Ubuntu (to scratch an itch). I spoke to the hardware manufacturer on the way. I ended up doing some contracting on Linux compatibility for some of their other products.
I began playing video games... and in the last four years from that I've gone through a full time job as a journalist in that field (award-winning :P), gained a lot of experience running large (70,000 person) events, consulting for companies that create games / hardware / events, and now work in marketing/various other areas, all in that same industry.<p>Just because I played games online.
I created a social networking software package, initially intended to be downloaded and used behind their firewall by small and medium companies for free (<a href="http://www.jouzz.com" rel="nofollow">http://www.jouzz.com</a>). I am currently in discussions with a large corporation that wants to implement it, paying licenses for all its employees!
I accidentally made more money than I planned on when I created a website to sell those Chronotebooks by Muji (<a href="http://www.coolhunting.com/design/muji-chronotebo.php" rel="nofollow">http://www.coolhunting.com/design/muji-chronotebo.php</a>). When they were first offered, the company only sold them in their store or over the phone. I guessed that there would be people who preferred to buy over the internet (as it was pretty popular with blogs when it was launched), so I did the dirty work of ordering in bulk over the phone, and then selling individually through a website.<p>I didn't think it would be that popular, but it was around Christmas time when I started it and I used the profits to buy myself a motorcycle. The funny thing is sales dropped sharply after Christmas, so I shut down the site. It was really a fluke that it worked out.
I built some hardware a few years ago for hobby projects.<p>Someone came onto a forum asking about a way to read a certain sensor so he could integrate it with his software. My circuit happened to do what he needed, so I made a few minor mods and became his hardware supplier for a few years.
Coming to this late but...<p>This happened about 10 years ago. I was out in Chinatown and came upon a knock off of a Transformer I wanted for a long time (G2 Laser Rod Optimus Prime). I bought him on the spot for 4$ and took him home. When I got back, I wandered onto Ebay and noticed it was selling for quite a bit of money. I went ahead and listed it (with specific mention of it being a knockoff) and left it there.<p>7 days later, it was sold for USD 50$.<p>I later found the company that was importing them and bought 30 from them. I went ahead and made quite a bit of profit (for a University student anyway) before getting out of that game.
Blogging.<p>I have lots of posts that rank well for obscure technical terms in programming languages and computer science.<p>I have a comfortable job (I'm a prof in CS), so I don't really need the extra money, but to my surprise, I get about $300/month now.<p>That's up from $10/month a year ago.<p>If it keeps growing like that, I won't be able to "ignore" it for much longer.<p>At the moment, I'm doing it all with Google AdSense and book referrals to Amazon.<p>I'm sure if I spent more time on it, I could do a better job of monetizing it.<p>But, I'm not even sure what I'd do next.