Planks are pretty good. I'm a huge fan of crunches. If you have a balance ball, crunches on a balance ball will target your abs better than traditional crunches (will also help work stabilizer muscles). My favorite lower ab exercise is to lay face down over a balance ball. Walk yourself out with your hands until the balance ball is under your shins. Roll the balance ball in and out with your legs (the motion will resemble a reverse crunch except that you're face down- you're basically bringing your knees into your stomach).

Sent from my BlackBerry 9800 using Tapatalk

Modified CG since 11/5/11
CLEANSE: VO5 Vanilla Mint Tea Clarifying, DevaCare No-Poo, CHS Treatment Shampoo
RO: DevaCare One Condition, SS Caitlin's Conditioner, Mop Top Daily Conditioner
LI: SS Repairing Protein Treatment, CHS Silk Leave-In
STYLE: Re:Coil, Curl Keeper, Deva Ultra Defining Gel, Curls Rock Amplifier and Strong Hold Mousse, Sweet Curls Elixirs Okra Gel and Hard Hold Gel, SS Curl Enhancing Jelly and Firm Hold Gel