Second Life participants are, by the way, required to be 18 or older. A second version, Teen Second Life, is restricted to residents aged 13-17.

Seriously, there's money in this?

A surprising amount. Though one can participate on SL indefinitely with a free account and without spending any money on goodies within the game. Linden Lab posts weekly SL economic stats on its home page. Analyzing those numbers, writer/analyst Tristan Louis suggests that the 35% to 40% of SL residents who logged into the system during a recent 60-day period spent an average of $50 to $60 per week -- that's real-world U.S. dollars -- in Second Life. Louis estimates that per-day spending in Second Life is just north of $115,000, and it's rising.

Who's making that money?

Linden offers premium accounts, which provide for property and a small Linden Dollar stipend, and leases land for development. Owning a patch of terrain (land or sea; some of SL's most impressive constructs are underwater) gives regular residents a place to keep their stuff as well as a place for SL friends to check in, leave messages and so forth. There are charges for uploading items or material and for placing in-world classifieds.