See
http://forum.bitcoin.org/index.php?topic=21965.0I just wanted to share with you all a pyramid I joined just a moment ago. The more people that join in, in the 12 hour window, the faster the payouts and more frequent as well. Basically all you do is send in BTC to a specified address FROM YOUR WALLET ONLY, not a pool, and wait for your payout.
Payout is 1.5x your original deposit. "Half the remaining balance at the end is refunded preportionally to those who did not get paid".
You should totally check it out!