Oblique crunches..?

Barbell squats!!!

Actually, my favorite isolation exercise for the obliques is dumbbell side bends. My wife started hers with 35lbs for 3x10 for reference.
http://www.exrx.net/WeightExercises/Obliques/DBSideBend.html


These have really helped my core stability.

I do an exercise that is even better (from the 6-pack in 6 weeks video).

Stand with a 5lb weight in your hands, arms extended to the ceiling. Step your left foot out to the side as far as you can and bend to the left with your weight. Move your feet back together, and do the same for the right side. Repeat.

I hate doing any ab exercise that requires me to have my tailbone on the floor. That stuff hurts! I do a lot of standing ab routines and Turbo Jam's Ab Jam video is really fun. There's 10 minutes of standing abs and then some floor stuff which you can do or not.... sometimes I do, sometimes I just do the first 10 min. then repeat.

>isolating obliques
>i seriously hope you don't do this

The obliques really aren't meant to be soloed out since they work as a team with the rest of the core.

I would recommend doing compound lifts such as: Squats, Deadlifts, Planks.

I go to a core class where we do side planks, and they are killer. Try 4 and 5 on this website--we also do 5 with 3-5lb weights.

http://blog.sixpackatsixty.com/2011/05/20/abs-and-core-exercises-–-beyond-the-basic-plank/