I'm hoping that anyone who is interested can identify that my selection algorithm is indeed provably fair. I'm also hoping to get the word out about my site! The site is called Satoshi Pot.
The url is:
satoshipot.org.
On the main page (after clicking "play"), there is a Fairness tab that describes how it is provably fair, and includes a link to a verification script. Here's a summary:
We have hour-long lotteries. People can purchase tickets by signing up and sending bitcoin payments to their provided Ticket Address. Any payments that have received 1 block confirmation by the end of the round will result in tickets being awarded to that user. At the end of each round, we use the hash of the most recent Bitcoin block to seed a Pseudo-Random Number Generator (PRNG). We then sort all the entries alphabetically by username (all usernames are unique), and run our selection algorithm using the seeded PRNG. This creates a provably random outcome so that nobody (including us) can cheat the system. Please let me know your thoughts! And of course I'd be thrilled if you played as well