The Onion Pool is an Ether mining pool that currently charges no fee. It runs on a prop payment system and rewards miners with the block tx. fees as well. The minimum payout is 0.01 ETH.
The pool is not the best, but good enough to be able to use it. The balance is updated with a delay, but at least it is updated, the interface is clear. However, I would prefer to switch to another pool.