Whether climbing's your thing or you just enjoy throwing a bit of iron around, the ProTips series contains some great information. The DVD's available from a number of stores (if you're in Australia, try Rock Hardware); but for a taster, take a look at Jared Roth discussing the benefit of hangs [streaming, 10.3mb .flv download].
On holds, rocks, bars or doorframes - it's a great exercise (personal favourite - the slippery flat surfaces of a power rack).
NB : for more information on the progression of hangs - as well as the exercises themselves - head over to Metolius Climbing. Excellent article.