Before I start I'll say the following could be a coincidence but if so it's one heck of one.<p>On Sunday I opened up the App Store software on my Macbook Pro. I started browsing through applications and came across an app named Boom.<p>I did NOT visit the link to their website, I did not do a search for anything about them. I simply went on looking through the App Store at other software.<p>Yesterday I was reading HN in my NetNewsWire software and saw a article about "best practices for signup forms". I clicked the link, the article opened up in NNW's browser. Low-and-behold, there was a fetchback ad (the only ad) on the page for Boom software offering me a 25% discount on the purchase of the software.<p>Here is a screenshot http://www.flickr.com/photos/65099140@N04/5927227432/<p>Is this a coincidence? Maybe. But it's one heck of one, considering there's over 90,000 apps on the App Store, and Sunday was the first time I had ever seen or heard of Boom.<p>Maybe the software developer is tracking users via some script/code passing information through the App Store to them? I don't dev Mac apps so I'm not sure if/how something like that would be possible.