Quote Originally Posted by Baba Ga'on
Bench presses, or anything involving the chest tend to improve those muscles, though you'll also be training your chest muscles themselves, of course. Pullups, too, and I'd agree with SwordsMaster in saying that they put more strain on the dorsal muscles than do chest exercises and so provide better results.

On the note of pullups, how to exactly to attach weight to the waist when your gym only has machines (you know, Nautilus, LifeFitness and all that jazz) and barbells and dumbbells? I do 3 x 10 pullups right now, and am planning to increase that to 15 - 20 in the future (I've just come off a long period of inactivity) but I'm kinda curious as to this.
To attach some weight to you, get a weight disc like one of the ones used for barbells, string a belt through it, and attach it to another belt (one of those hard, weight-lifting ones) that you then, attach to yourself like you normally would.