When the app store first opened there were many apps I downloaded and then subsequently deleted as my iTunes library of apps was getting too full and unmanageable. I know you can have practically endless pages of apps but to make it difficult to weed through the apps you're interested in placing on your iPhone and those you're not. I'd delete the ones I wasn't interested in anymore off my iTunes page. Fast forward a few weeks or months and I'll see an app. I'm interested in either due to an update or other modifications but not exactly sure if it is a prior app I've owned or not. It would be the type of app I'd download for free but see it is now charging, sometimes a pretty hefty premium. Instead of clicking purchase and hoping it was a prior erased app, I now click "review this app". For example, I recently did this with Air Sharing. I downloaded it when it first came out (and was free), didn't really use it, erased it, but now with the recent upgrades/improvements, wanted it again- but not necessarily at the $4.99 being charged. If you have not purchased the app then, of course, iTunes will not let you review it and a screen will pop up telling you so. If you have purchased it or downloaded it on a prior occasion iTunes will pop up the ratings page even if you have given it a prior rating. I click cancel for that screen when it does so and I then know I'm good to go to click the update/download for free.