Cyanogenmod
I love using this software on my rooted Android phones. G1, Nexus One and now G2, the added functionality is amazing!

Fuelly
I track my gas mileage religiously.

woot
Awesome and addictive, I wish all eCommerce could be this fun!

Twin Cities Maker
These folks are doing some cool stuff in town and have one of the best hackerspaces that I know of. When will someone make a real Spoonbridge and Cherry catapult? I don't know, but they will probably do it here.