A lottery style gambling site with 99% payout of a monthly jackpot to an almost always sole winner.
The winning selection of lottery numbers for determining the winner or winners are the results of the Western Canada Lottery Corporation draw.
The Bitcoin transaction hash of the 1 BTC purchase is used as the "pick" and to see who sent it, and therefore know where the winnings should go. The algorithm for converting the winning lotto numbers to the characters in the entrant's Bitcoin transaction hash is documented on BitLotto's site.
The service was launched on April 6th, 2011.
When a winner is paid, the funds are sent to the Bitcoin address that bought the winning entry. This method is not compatible with EWallet services and payouts will not go to the intended recipient. The site does warn about this but some users who use an eWallet might not realize the issue. The site clearly states many times, that as long as you run Bitcoin software on your own computer, you will not run into a problem.