Google Earth
"Google Earth combines satellite imagery, maps and the power of Google Search to put the world’s geographic information at your fingertips. Fly from space to your neighborhood. Type in an address and zoom right in. Search for schools, parks, restaurants, and hotels. Get driving directions. Tilt and rotate the view to see 3D terrain and buildings. Save and share your searches and favorites. Even add your own annotations." -It's a free download, relatively small for what you're going to get, that enables you to go sightseeing all over the world. I have to say, I LOVE this. Give it a try. I'll post a few of my pictures once I download it today.
Note: This is the coolest! I'm having so much fun with this. Gosh, I'm such a geek, but I don't care. Seriously, download Google Earth if you at all possibly can, and play around with it. I love how it zooms all over the place.
Tokyo, Japan
Nuremberg, Germany
Rio de Janeiro, Brazil


Should be mentioned that it was available as “EarthViewer” by Keyhole since 2001, then acquired by Googs