any tips on a great ab workout?

ab-wheel

Search it on youtube, Just one bit of advice though... do whatever you're going to do till it hurts like you can't do it anymore, wait 30 seconds, do it again and repeat. When you feel the burn, that's when it's working.

Ya, I need a good ab specific workout. I already work my abs with squats and deadlifts, but I'm vain enough to want them to have their own day. And I want more core strength.

weighted ab crunches on a decline bench.
(weight on the forehead or further back, not on the chest, which is too easy)

Situps and back extensions on a roman chair. Weighted.

Fuck that. Do it untill you can't do it anymore, and do 20 more reps. Then wait the 30 seconds and repeat.
I can easily get a mild 6 pack by doing this every once in a while.

six packs are created via abdominal skin thickness reduction.
Everyone already has a six pack.
yes, you too , and you too , and even you.
Uncovering it is not easy, however.

I hate seeing people do ab workouts, but a great one recommended to me by a former olympic lifter is this:

Lay flat on your back, place a 25 pound weight on your ankles. Rise your legs up until they're level and while keeping your legs up at this same height, do a traditional crunch. I doubt you will even do 10 of them.

This.

Start on your knees, then start doing them standing up.

You can do these every day, you don't need to have a single day dedicated to abs. I use my ab wheel everyday.