Don't really use a lot, but there are tons out there.
Games - Only two (three) I really play, although yes, everyone is tired of the birds now. haha
Angry Birds - Just an addictive slingshot, tumble the tower game.
Angry Birds Seasons - Same game, but with seasonal themes
Frozen Bubble - three in a row, launch based game
Apps I use
Shazam - Fantastic music app. Hear a song but don't know or can't remember the name ... or who sung it? Just hit Shazam, hold your phone up to the song and BAM ... Title, Band and Album.
Flashlight - Turns your camera flash into a great, bright flashlight. Great for those unexpected power outages.
GOOGLE Earth - Incredible map tool. Check out Italy on the comfort of your sofa
Mirror Mirror - Turns your phone into a mirror. great for those impromptu, nose hair checks before a date
Touch - Multi person trexting. Great for this site actually. May start a group. We all join and whenever someone posts a text, it goes to everyone in the group.
Hey Tell - Voice messaging. Instead of typing you talk and hear. Notifications come through like a text message, so you don't have to listen right away, if you need to wait.
Those are the ones I really use. And I haven't been on the market to look for more in a looong time. God only knows what is there now.