I too use Facebook every day, as well as Air Sharing, maps and some knitting apps that I've downloaded.
I use Yelp fairly often as well, probably weekly, and then I have a number of free games that I play on and off - I like to rotate - especially on the subway or bus. I also downloaded MobileChat, a multi-chat program, so that I can have my google chat and AIM contacts in one place. I like it better then I do AIM, but I have that as well. To date MC is the only app I've paid for, but aside from games that I downloaded and I did not like, I have yet to get an app that I don't actually use.
Oh - I use my flashlight all of the time!
John - what's city transit?