Google Maps continues to surprise me. I used to use Yahoo Maps, but once Google introduced the satellite images; I started playing with it and using Google more and more. Now they've added a hybrid maps feature which shows the satellite view of an area, but superimposes major roads onto it. Cool!
While were on the subject...I've also been playing around with Housingmaps.com a bit recently. If you haven't tried it yet, I recommend checking it out. Harnessing the power of Craigslist along with Google Maps, this is a great way to search the current Real Estate listings geographically. While it only shows the properties that were posted on Craigslist and not the whole MLS, it's a great idea and hopefully it will be a sign of whats to come.
You can search the for sale, for rent, rooms, and sublet listings in a certain price range for each area and they site will plot them on Google Maps. When you click on each marker, the headline (which links to the Craigslist post), address, photos, and contact information are displayed.