Although I play a lot of TF2 I tend not to trade much so it was as a surprise to learn of the TF2 raffle. Just like real world raffles people enter by buying tickets for a chance to win a major prize.
As an example this raffle offers a 1 in 150 chance of winning a Max's Severed Head, a TF2 hat which is worth roughly 50x the ticket price. In dollar terms the ticket price is around US$0.50, and the hat worth ~US$25. In any case a 66% margin is pretty tidy!
From a former World of Warcraft player I learned that a common gambling game in WoW is the roll game where one player acts as the house, the player gives her $x and using the in-game /roll function to generate a random number from 1-100 the pay back is something like 1-66 = loss, 67-97 = 2x wager, 98+ = 3x wager.
What's interesting about using in-game currencies is that in some cases the link to real world value is not obvious. Not all games provide a direct conversion mechanism between real world dollars and in-game currency so players may perhaps gamble without the mental association with real financial gains/losses.
I also wonder what other real world gambling games have been ported to virtual worlds. How long before we see a Swoopo implemented with in-game currency?
What other gambling mechanisms have people seen in virtual worlds?
Going further - what other seedier real world activities have been or are to be ported to virtual worlds?
There's a virtual crap tonne of research suggesting that virtual currencies is an emerging money laundering threat but I'd be interested to know of real instances of it occurring.