Is there a catalog of Lego building techniques?
Swooshable has a great collection of SNOT (studs not on top) and advanced techniques, it is probably the closest thing you will get to an online catalogue.

They seem to have updated their SNOT section with some really pretty renderings, piece information, videos and step by step instructions. Most of the articles for advanced techniques lead to external sites.
There are also techniques for making LEGO fonts and an introduction to building techniques and many other cool things.

There are a also few books I can recommend, they are all from the same publisher (no starch press) but are probably the best resources.
The Unofficial LEGO Builder's Guide, 2nd Edition
I have both editions but I prefer the second as it is in full colour and much more compact. It covers among many other things:

Common vocabulary
Structural tips (Building round walls, bracing, columns, etc.)
Parts that can be used as substitutions
Advice on planning builds
Mosaics
Sculptures
An index of commonly used parts.


The Unofficial LEGO Technic Builder's Guide, 2nd Edition
The best book there is for Technic builders, it covers the basic concepts, mechanics, pneumatics, motors and other more advanced concepts.

The LEGO Technic Idea Book: Simple Machines
Also covers Technic concepts but from a minimalist perspective. The techniques are presented purely visually so it is up to you to work out how they work. It's a good book to flick through to get inspiration.


If you aren't looking for anything in particular, you can also have a look at the top questions with the 'building' tag on this site.