ArsBitcoin

A mining pool originally created for the Ars Technica community. The pool is open to the public.

This pool pays out using a Shared Maximum Pay-Per-Share system. This means that it credits miners with a constant BTC per share based on the current difficulty. It then attempts to pay out miners as much as possible when new blocks are found. This method prevents pool-hoppers from getting a higher than average value for their shares. More details about payment system on the homepage or bitcoin forums.

The service was first available on June 15, 2011. It was announced on the Bitcoin forums on June 17th, 2011.