Topcashback are offering £33.33 when you register and play through £15 with Karamba casino. A word of warning - if you accept their offer of a free bonus when you register you have to play through the bonus 20 times before you can withdraw anything. Either way you still get the £33.33 cashback from Topcashback whether you win or lose so it's definitely worth doing as you're guaranteed a profit of at least £18.33.

I was lucky and after playing through the bonus 20 times I had £85 in my account that I withdrew! So I made over £100 profit including the cashback :)

Topcashback exists in UK and USA. I'm based in the UK so I know that this offer exists here, but no idea about whether or not it is available in the US as well. I'm guessing probably not.