123D is a great little 3D modeling application that is simple to use. I can spend hours playing with this software.
Autodesk Design Review
Design Review is one of best application for sharing your design documents.
No AutoCAD, no problem. DWG Viewer allows you to view and print dwg files from any computer for free.
Ever wish you could design a dream house or play Architect for a day? Now you can with the new Homestyler by Autodesk.
Check it out: Homestyler
Check it out: AutoCAD WS