Climbing Links
The most extensive database on Mexican crags currently on the Internet, this site lists nearly all the routes in the Potrero. Check out the info on La Huasteca and El Salto as well: there are complete topos.
This Monterrey area climbing shop has some interesting info on various adventure first ascents of the peaks and walls behind town. Check out how the bold locals are upholding the trad style in this day and age of sport climbing.