Over the holidays a few friends got an iPhone or iTouch and asked me what apps I use the most. Looking at my iPhone now I have four main pages (three full) of apps and links. Unsurprisingly to folks in the audience, they are mostly games. I've grouped them up so you can skip around. All links to apps will open up in iTunes so you can get more info.
Sportacular - Sports scores. Set your fave teams, etc. one screen. Very nice.
Things - ToDo list manager. I use this on the Mac. Can sync, I don't
Quordy - Boggle for the iPhone.
Tris (no longer available)
Sol Free Solitaire - Exactly what it says. A few free Solitaire games.
Texas Hold'Em (Apple version) - Fun, with some flaws.
Enigmo - This is a puzzle game requiring you to solve fluid puzzles. Fun!
Chopper - My first game on the iPhone; Choplifter remake.
Crazy Tanks - Drive around, blow up tanks.
Fieldrunners - Played any of the build-a-maze-with-turret games? Here ya go.
Brothers in Arms: Hour of Heroes - Call of Duty-esque on the iPhone FPS.
Galcon - A fun RTS, including multiplayer!
WeatherBug - Nice weather app, allows for bookmarking of favorite cities.
Who is Hot - Shows the weather at your Contact's location. Can click on their location for more info.
Game Related ~
Warcraft Characters - Play WoW? Keep your characters (or your friends) on your iPhone
Score - Board gaming scoring app. Helps!
Geocaching - Yes that. GeoCaching.com's app. Bring your GPS anyway.
Facebook - Not my fault!
Streaming Music ~
Pandora - Streaming music. I've blogged this one to death.
TideApp - Good for when your going to the beach
SoLuna - I had tides, must have Lunar phases too!
Missing Calculator - Programmers calculator; shifts, binary, hex, etc.
myLite Flashlight - Amazingly useful. Lights up a hallway nicely during power outages.
Lightsaber - *cough* For the kids
Easy Wi-Fi - Helps to log in to the AT&T free wi-fi zones.
Google Earth - Not as much fun as I thought, but still there.
Constitution - US Constitution
Declaration - US Declaration of Independence
I'd also check out Meebo for a multi-client web-based IM. Haven't seen an Adium/Trillian clone on the iPhone yet (and not sure I'd want to!). This does well enough if you need access to IM.