I've always been fascinated with the game theory, math, and psychology behind these schemes. There's a bunch of variations of the auction model that can guarantee or nearly guarantee a profit. One of the more popular auction models is to make the winner the person with the lowest unique bid, but it costs to place bids.
Actually, no. In those games, its the lowest unique bid. check out http://www.bidster.com/ . This way, if more than one person choose the lowest bid, then those cancel eachother out, and the next lowest, but non-duplicated bid wins. There's a large number of these sites out there actually, but none-the-less a very profitable business. Might be less of a lottery though, because one could claim its a game of skill.
