Here are my favorite things about my ipod touch and how I use them:
(Almost all are free and available in the App Store.)
An improved twitter with geolocation (my friend accurately refers to it as "the voluntary stalker network")
Also, the barebones http://m.brightkite.com/ has proved useful to me.
Absolutely horrible process for importing cbr/cbz files, but being able to read Watchmen while waiting in line at the barber shop this week was all kinds of awesome.
For finding used musical instruments.
I don't typically like apps like this, but it seems to work really well.
Of the many musical apps I have evaluated, this is the only one I adore.
Google Sync for iPhone
Free, fantastic and worth the long wait. (I believe it came out yesterday.)
I don't use MobileMe or Exchange, so I've been totally outta luck connecting my google app data with my ipod.
Better interface than the bloated netflix site.
It'd be nice if it had an offline mode or even a sense of grace.
I've used it for tweaking and troubleshooting my wifi networks.
Speed Test app
Great port of the speedtest.net site.
Though my provided server was down once and the app just stalled.
I don't use this much, but its proven very useful on a few occasions.
I used to use index cards for my action/to do/whatever list before I got this app.
The integration with the mac app is superb.
I haven't needed to use this yet, but I was impressed with the transparent keyboard interface.
Good implementation of the twitter.com site.
Mocha VNC Lite app
Great VNC client!
Solid use of the touchscreen interface.
I have only tried a couple of dictionaries, but this is the one that's proven the easiest and fastest.
I only got this a few weeks back, but I really wish I had known about it sooner.
Let me know what you think or you have something I should check out!