Where To Pool Mine Bitcoins

2017 Edit: Antpool seems to be the most profitable now Ghash.io has closed its doors. You can still use CEX.io to trade Bitcoins but they no longer run the mining pool

So if you have decided to mine Bitcoins for me there is only one place I would go, it has the fastest pool rates on the internet and controls the biggest share of Bitcoin mining. A block is roughly solved every 17 minutes which for Bitcoins is fantastic.
  The site is cex.io which is affiliated with ghash.io here you can join the mining pool and you can even deposit, exchange or buy coins or hosting power in GH/s, I also believe if you have lots of power you can sell you GH/s to other people. Go check it out