Several companies are offering free bingo in the hope of attracting users to their paid for games.

I have won a couple of hundred pounds just doing free bingo.

The sites I use currently are:-

Cheeky Bingo – http://www.cheekybingo.com
Costa Bingo – http://www.costabingo.com
Foxy Zero – http://www.foxyzero.com

There are other sites with similar rules such as:-

Posh Bingo
Prize Bingo

The only downside is you need to fund your account before you can withdraw your funds.