I'm not sure how long its been out but I just stumbled on Google's new 3D drawing application called, "SketchUp".
I downloaded and trialed it out today and all I can say is, it is very, very cool. I'm not an architect or mechanical engineer and you don't have to be in order to enjoy this application. It is extremely easy to use and their tutorials are easy to follow in order to get going quickly.
I showed it to a friend and she said, "all my engineer friends can kiss their years of experience using other drawing software goodbye".
Go check it out and if its not something you want to use, I'm sure someone you know will.