I dont climb myself, but have several friends who do, wish I could but my joints are to messed up

...and bodyweight exercises seem to be the optimal method( I consider climbers probably the strongest people pound for pound). Mass is useless, as it will weigh you down, the ability to control your own bodyweight as optimal as possible is what will help you.
If you cant do a pullup, then you do the negatives and work from there. I have seen them do a pullup/chinup combo, do a lift, then as they reach the top they swap grip to the other one. Requires some balance and speed, but again, useful for climbing aswell.
At the local club, this guy is a huge youtube favourite:
His main page:
http://www.youtube.com/user/Fazioenterprise