How do I workout my oblique mucles?

I want to workout the muscle in this picture

http://www.free-ab-workout.com/images/ExternalObliques-correctedTEXT.jpg

Basically I already have the six pack and want to workout the muscles to the side of my abs but all the exercises that I know of feel weird, I just don’t like them. Can you guys tell me of some exercise that you know will workout those muscles good?