Lego Digital Designer

New version 2.0!

Version 2.0 of LEGO Digital Designer offers many improvements and great new features, including:
Improved Building Experience
Optimized connectivity
Vast performance increase
New brick palette system for easy use
New brick assortment
Various templates for getting started
New backgrounds in view mode -based Macs.
Improved virtual Building Instruction generation

http://ldd.lego.com