Because the sum of what I know is dedicated to multiple other sites on the internet, I must mention their contribution out of respect. These people have worked longer and harder then I have to bring you better information, and for that I thank them, so with out further ado here is a list.

IndoorClimbing.com - I found this site to be most informative, and filled with useful information. They also have some other useful information such as gym listings, lots of links, and a climbing simulation video game.

Metolius Climbing - This site is filled with alot of good information, and lots of how-to's, also if you have a couple bucks to spare they also sell some good climbing equipment, holds, and a really nice climbing simulator.

SolidRock Wall Systems - SolidRock Wall systems offer some good documentation as far as building climbing walls goes, but they also sell their services of building climbing walls.

The Indoor Climber's Resource - This site is straight up information on how to build climbing walls, and holds, no fancy interface, just in your face here is how you build it, the way I like it =).

The Climbing Wall Resource - This is by far my favorite site, it is all how to build at home techniques, and has a great tutorial on holds, and not just wooden, also resin, and plastic. The home climbing wall database is also very cool, because some people have some really great ideas, hat is off to this site.