I do not have the iPhone yet probably going to for xmas but I do have the ipod touch and apps I have are
Facebook
IMDB (international movie database)
Kindle (i have a 1st gen kindlw too so I can read myu books both places)
Pandora
GI Monitor
All Recipes
Craigs pro (free version of craigs list)
Some airkast radio stations ( I live in OR now but like to listen to radio stations from RI)
Solitare
iJewels (like bejeweled)
Micromedex Drug information (lists side effects etc of meds)
WebMD
Sudoku
msnbc.com
Twitter
Mancala (marble time game)
Crackle(free streaming movies and tv shows which change what they have to offer)
GH@home (good housekeeping free tips)
MyFitnessPal (calorie tracker water intake, exercise calorie burn info)
I only get free apps so those listed above are all free to get I have others too but they are the ones I like the best I also have tried some others and it doesnt upset me if I dont like then since they were free =) most apps that I find I am interested in have a "lite" version which is a free version so helps you from testing the waters before getting the full app
enjoy