-Apple's remote app is very useful for me, as well as iTap for a wireless mouse and keyboard. Mocha VNC lite is also useful for controlling a computer.
-Air Sharing is great for storing files on your iPod touch, and viewing them from it. It's basically like a wireless USB drive
-textPlus is convenient for free text messaging
-Stanza is a great, free, Ebook reader
-NetNewsWire is a very simple RSS feed reader, and I rely on it a lot, especially since the touch doesn't have always on internet. I can download some news when I have a connection, and read it later when I don't.
-Pandora Box is useful for finding new apps
-myHomework is an excellent app for organizing your classes and homework if you're still in school
-urbanspoon is great for finding a place to eat
-Graphing Calculator is a great graphing calculator, if you need one.
-Pandora and Simplify Music are nice
Here are some of the games I have:
-Cro-Mag rally
-Doodle Jump
-Enigmo
-Flight Control
-Gridlocked: Rush Hour
-Real Racing
-Sol Free Solitaire