Mmmzr is a new advertising site. It claims if you advertise there you'll get 'twice your money back'. The way it works is by charging an exponentially higher fee each time, so the first advertiser pays $1, the second pays $2, the third pays $4 and so on. At each step the previous advertiser gets a portion of his original money back until after 2 iterations you get 'double your money'.
Seth Godin says "sites like this are going to keep changing the rules." Unfortunately, Mmmzr seems just like a variation of the ponzi scheme to me, a classic form of fraudulent investment scheme that relies on ever increasing suckers signing up to pay out the people at the bottom. At some point the biggest investors should hit a ceiling and won't possibly get any money back, while the owner of the site gets rich. Luckily for Mmmzr, they should get away with it as they can claim they're 'selling advertising' rather than just taking money for abstract investments.