Here's a list of notable apps that I use a lot on my iPhone.
Facebook - I like the new 3.0 update, can't wait for push notifications (actually would like push notifications on a lot more applications but since I can't say how long it takes to edit/develop an app with push and the service only came out.....like less than 6 months ago, not complaining). Quality app, use it every day, big improvements over the last version. (Free)
Tweetie - Just purchased Tweetie 2.0 and feel it is a wonderfully polished and easy to use application, well worth the money.
Canabalt - Great game, also worth the money. Could use a quick-pause tho, and maybe a small amount of backstory to it (What are the crazy things that fall down right before I run into them? I don't like those things. Are they bits of alien robots?)
Sketchbook Mobile - Just grabbed this last night. Makes me want to sit somewhere quiet and just doodle or actually sketch something. Improve my artist talents or something. Hawk drew an awesome pic on this when he was bored and i wish i could do something that cool.
Minigore - Don't play this as much, but really really nice graphics and, again, wish I had a backstory or something.
Snapture - I honestly think that this was kinda a wasted purchase, as the zoom doesn't zoom just screws with the resolution a bit to make crappy photos. Cool features, just not a default Camera app replacement. I am giving it a try tho.
Ocarina - Smule is a neat company that makes some really high quality apps (like AutoTuning "I am T-Pain") and the Ocarina is one of them. Finally got the hang of playing kinda well, still want to print out some sheet music and try to memorize something (there needs to be more music out there to play for it)
some QuickThoughts -----
Dropbox - GREAT!!! Although small errors in reading some (SOME) .txt files, so i have to save some important documents in .rtf for some reason. I love having access to important files quickly and on my phone is pretty nifty too. Great app
The Weather Channel - Just replaced the default Weather app as my front page weather informer
Shazam - Haven't gotten a chance to use this since driving in the summer. Maybe when i go home next week and am taking the car out a bit. I miss my radio stations (country sucks)!
Rope 'n' Fly Lite - Great game (thanks to Ben at work for introducing Lucy and me to it and causing us to waste a lot of time) and maybe I'll buy the full version. High score = something like 784.4 ft. Go Go Spiderman!!!
