There have been a ton of sites popping up using Google Maps to show things like traffic conditions, apartments for rent, etc. Here are two that I found that seem pretty nifty.

Cheap Gas
Yeah, we are all tired of paying $2.50 for a gallon of gas. I always enjoy those eureka moments when I happen to find a gas station that is about 10 cents cheaper than everyone else.

This site lets you choose a state and see gas prices that people have submitted for various locales. It also lets you know when they posted it because we all know that the price of gas can jump 5 cents in a day.

IP Traceroute
I used to have this program on my computer that would trace IPs and show me a map of where that IP is located (or in the general vacinity).

This site does the same thing, but with Google Maps.