I discovered this 3-D chat system a few days ago, and I'm having a blast.

IMVU

It's a lot of fun to fool around with your avatar. They start you off with some free "credits" to buy hair styles, clothing, and so on. You can get quite a few more credits by chatting with somebody at least once a day for four days in a row. Then you can buy one of a huge selection of 3-D chat rooms. (Of course, they want you to pay real money to get even more credits, but that's not necessary at all. I haven't spent a cent, and I'm perfectly happy with what I have.)

Here's my home page (nothing fancy):

Link

To make sure this thread isn't just spam -- I swear I don't work for IMVU, I just think it's cool -- feel free to offer any other interesting web sites you might like to share with us.