How about abs, seen as I've lost most of my weight off my stomach I think it would be a good idea.
How about some normal crunches, some side crunches (so do a normal crunch and sorta lean to the left/right so you are really targeting your waist), leg lifts (lie on your back with your legs straight, lift your legs up off the floor and hold) and the (dreaded) plank (google this if you need to as is hard to explain)!!
People can do any many or as little as they like.