Autodesk has released a free-for-use true 3D solid modeling software called 123D. The massive 521Mb download is not the only thing you get; there's also a pretty comprehensive online repository of whole objects and basic components you can draw from to create awesome things.
We think 123D is a big deal, as it's relatively easy interface, no-charge software and comprehensive model repository will enable many more people to get into 3D modeling - and possibly 3D printing. Beware, though, because many of their models are not readily printable on current home 3D printers due to overhangs, colors limitations, etc. We're not quite sure why Autodesk would produce and give away such a powerful tool, but nevertheless it's there for you to use. If you're on Windows.