We wrote about Bricksmith before on the MAKE blog. It's a really cool open source LEGO building program for the Mac. Version 2.0 boasts better rendering and a cool Minifigure generator.

Bricksmith allows you to create virtual instructions for your Lego creations on your Mac. The magic is based on the LDraw library, a collection of 3D models of Lego building blocks created by enthusiasts from around the world. With Bricksmith, you never have to worry about running out of parts!

Get your free copy of Bricksmith 2.0 [Mac only, sorry!]