Please find here a list of Ethereum Mining Pools.

At current prices (ETH/$ 12 aprox) it may be reasonable to think that joining an Ethereum mining pool may be worth it. Even though you may think it may not provide a meaningful revenue stream, I personally think any support for cryptocurrencies and the development of a new monetary system is important, and we, as individuals should aim at adding our "grain of sand" to move towards a better decentralized world and economic and financial system free from the powerful and away from the gravitational pull of big banks and the powerful.

This is a list of Ethereum mining pools as found in the Ethereum community;

No registration required
1. http://ethereumpool.co/ - 0.8% fees. Payouts released 2 times a day for balances higher than 0.5 ETH.
2. http://dwarfpool.com/ - 2% fees. Payouts released 4-6 times a day for balances higher than 1 ETH.
3. http://weipool.org/ - 0% fees. Payouts released every 24 hours for balances higher than 1 ETH.
4. http://ethpool.org/ - Predictable Solo Mining pool. 0% fees. Payouts after 10 confirmations. More info on @dr_pracomments below.
5. http://nanopool.org/ - PPLNS 1% fees. Payouts released 2 times a day for balances higher than 0.1 ETH.

Requires registration
1. https://eth.suprnova.cc/ - 1% fees. Payouts are up to the miner (Manual or Automatic from 0.01 ETH).
2. https://coinotron.com - PPLNS 1 % fees. RBPPS 4% fees. Payouts are up to the miner (Manual from 0.1 ETH).
3. https://www2.coinmine.pl/eth/index.php - 1% fees.