I have been meaning to start off a series of articles on the best exercises for each bodypart and a bit of a write up on each muscle group but I just found a great page with little animations of 70 core exercises
As you are probably aware the core of your body, your midsection has a lot of muscles. You use core muscles for bending over, getting up, standing, walking leaning to either side. an a host of other ways as well.
I have hurt my back a couple of times including once really badly earlier this year, (and a better way to warmup) and I am sure you know as well how hard it is to suffer along with a bad back or sides or abs.
So check out the exercises. They may help a bit with loss, they will definitley help your posture and how large you look and these exercises are critical for getting you in better physical condition