Abs like this:
http://heangkoing.homestead.com/files/M6.JPG
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A lot of squatting.
Incline sit ups with weights on chest then progress to weights behind head: 8reps x 4 sets or 6reps x 5sets
(much tougher but make sure your back can take it first)
Bulk off's
Various Gymnastic ab strength conditioning:
http://www.american-gymnast.com/tt/paralletteguide/page3.html
But you have to hav a *some what* low bf% to start with. You have to have your abs developed so that they *bulk* out and start to resemble brick work sticking out of a wall. Then when your bf% is low enough they show. Also why you see a bunch of stick thin guys with flat stomach's but no 6 pack, because they haven't developed those muscles.
That = good 'clean' as possible diet; and long drawn out cardio OR sprint intervals. Both work great.
Also got to lift weights in general.
Koing
http://www.geekfitness.com/