So Lauren Over on facebook asked for Tiger patterns. I did some searching and there doesn't seem to be a lot. But here is what I found:
Crochet tiger Kitty
I hope that gives you a starting point! Other suggestions would be to find a cat pattern you like and add felt stripes like in the first pattern. Or to add some every few rows by changing colors up to the side of the belly.
Here's a few tutorials on how to change colors: