The program is IMVU. It's free and gives you some free "credits" you use to make your avatar (and/or room and/or homepage) just the way you want it/them. The way they make money is from sales of additional credits to people who want more than you can get free.
Anyway, if you're interested in trying the program out, simply follow this link and check it out. (Full disclosure: you DO get additional free credits when your friends sign up). Then come visit my IMVU home page by clicking on my avatar image above. (Or just send me a friend request and tell me you came from my blog if you already have an IMVU account.)
One thing to beware, though. If you try to use their "add buddies" feature to invite friends (as opposed to sending to each friend individually), make sure you deselect your entire email address book before sending out the invite to people who may already have IMVU! I didn't do this and ended up spamming tons of people, including many Yahoo groups. Also, you probably want to deselect the "automatic reminder" option if you're going through the "add buddies" button (yeah, I didn't do that either).