google's listen is fantastic for driving down the freeway! searchable and queueable podcasts that you can save locally for when you have no cell service. Not sure how many can be queued up and cached, but I've done two no problem.<p>Also, you'll want a task killer app, since you'll find that apps never "go away" until the system runs out of memory causing android to take over and kill some programs. My favourite so far is "Taskpanel". Additionally, for recording a GPS track, use "My Tracks" which is simple and enjoyable enough to use, lets you email the file to yourself when done.<p>"gpsstatus" is fantastic - the must have for a tinkerer! Also usable as a level, so no need to get one of the trillion level applications.<p>Believe it or not, the flashlight apps are very handy to have on the desktop, as they keep the phone from sleeping/dimming too soon.<p>HANDS DOWN the best application if you do any amount of texting or MMS, is 'handcent sms'. It is a fantastic program, and one of the nicest Android programs I have used. Can't praise this enough!<p>For twitter, 'twidroid' is my favourite. I don't do too much twittering, so am not sure the competition, but this one is speedy, feature filled and never bogs down my phone. You'll find that isn't always the case with android apps, so twidroid gets a nod for this (as well as handcent, it is rock solid).<p>If you use ampache at all, my buddy Kevin created an android app to stream from your ampache server. It's called 'amdroid' and is pretty decent. It's definitely a work in progress but it's fully functional.<p>'phonalyzer' is cool for seeing stats on your phone usage. Much better than any carrier specific graph on a webpage, and it's small enough to not worry about having it installed and taking up space. It's definitely what I call a "toilet" app, because that is about when I use it, however, it's nice to know my usage here and there! I guess that is praise, because it means I don't have to spend hardly any time using the app to get benefits from it.<p>depending on the android version/carrier/handset manufacturer, you may want to install 'spare parts'. It's a few more settings not found in the settings menu, but I think this only supplements handsets running android 1.5, but I am not sure off top of my head.<p>Finally, root your phone and install 'wireless tether for root users'. I kid you not, it's the most useful app i've used. You can't find it in the market, but a simple google search will get it for you, and you can just click the link from the android browser to install it. It has access control lists, WEP (better than nothing) and multiple concurrent client support. I love this application, but of course, use at your own risk as you have to root your phone to use it (not a problem for most handsets), and you may run up data charges fast if you don't have unlimited.<p>That's my main list, anything else has been tinkering. These have been installed/reinstalled on my phone since I have had an Android device.