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.
ConnectBTC is the most recent mining pool by Bitmain. The pool offers Bitcoin mining through a 0% fee PPS system. The pool subsidises the miner with an additional 6% for a total of 106% of the block reward. Payouts are done on a daily basis. The minimal earnings to qualify for payment is 0.001BTC.