RealCalc - replicates the classic Casio calculator layout and functions.
NubiNews - EXCELLENT free, open source offline news reader. It downloads the contents of various news sites and reformats them to display clearly and without fuss on your phone. Sadly it's no longer available on the market... but PM me and I'll send you the .apk.
FileExpert - View the contents of your SDcard, install .apk's,
share your SDcard over wireless, FTP or HTTP servers
Universal Remote - turns your phone into a universal remote over wireless, so that you can control your laptop/computer using the touchscreen as a mouse and the phone's keyboard. Useful when streaming NetFlix/youtube/etc with your laptop plugged in to your TV.
ColorDict - Best dictionary app ever.
Also, if you use Google Docs, Google have just released a
Google Docs app today. It's not much better than looking at the docs in the browser (in fact it still appears to use HTML5 to render the actual documents), but it is a little faster (and more convenient).
Don't bother downloading a separate location thing, just use Google Latitude (enable it via Maps).
http://forum.xda-developers.com/showthread.php?t=929193 <-- that thread might help too, but a lot of them are only for rooted devices, which you probably don't want to do until your warranty runs out. Actually that whole forum is badass.
If you do root your phone though, get FasterFix - speeds up GPS fixing by updating/refining the location of the satellites.
