It's inhabited by meerkats. Just don't be caught on the floating blob after dark though.

Steve Krug's "Don't Make Me Think" is an excellent book for web usability. Many of the principles in the book apply to good app design as well.

http://www.amazon.com/Dont-Make-Me-Think-Usability/dp/0321344758/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1199369216&sr=8-1