secondlife.com This is the homepage for Second Life. You can get the program free from the download page. You need a good computer and connection speed for SL to run smoothly, but even if it doesn't you can tweek it's various setting to help you. This is an online, interactive, social networking world where everything is built by the residents. You can try it for free, but give it time and explore. There is so much to see and do it's kind of overwhelming at first.
This is a building I created for 2 clients recently, and is situated near my own place in Sparta.