Second Life. For those who don’t have a first life.
Yes, while there are plenty of people who have no real life doing dumb things in a virtual world it is not any different than what the same people do in real life.
Second Life is not a game and the social networking aspect is just one overemphasized and oversensationalized part of it. It has a lot of the same uses and aspects of discussion sites like this one.
There are a lot of real business people making real money on SL as well as universities and government entities doing research and simulations that cannot be easily done in the real world. One simulation involves terrorist attacks and the dynamics of the aftermath. Classes in business, finance, science and other disciplines are also conducted using SL. And the answer is no, I am not a SL user. I’ve been on SL a couple of times through others and our institution is considering using it for marketing, advertising and some types of research.