Second Life is one of the largest “virtual” worlds online, with over 800,000(!) users as of October 2006 and it is increasing by 36% each month. It has its own currency and economy:
http://en.wikipedia.org/wiki/Second_life
Gambling is rampant there – you see casinos everywhere.
I found this article on “The Unlawful Internet Gambling Enforcement Act of 2006 and Second Life” very interesting, thought I’d pass it on:
http://secondlife.com/knowledgebase/article.php?id=291