1. Thanks.
2. Thanks a lot.
3. Thank you so much.
4. Thanks a million!
5. Thanks for your help. / Thanks for helping me.
6. I really appreciate it.
7. I'm really grateful.
8. That's so kind of you.
9. I can't thank you enough. (for extremely important things)
10. I owe you one. (this means you want/need to do a favor for the other person in the future)

Fact
During the making of the the movie Fight Club, actor Brad Pitt chipped his tooth. However, he did not get his tooth capped until after the movie was done filming as he thought it would look better chipped for his character      .. More >>