Made by the same folks you brought us the amazing 3D model search tool 3DFilter, Cadyou is a new venture that should enable a lot more model sharing. According to Cadyou chief Tom:
the idea is to create a wiki-like experience for 3d and 2d cad models where you can contribute, vote and edit all of the files on the site.
The site holds models in a variety of popular 3D model formats, including: 3DS Max, DWG, DXF, C4D, Lightwave, Revit, Sketchup, STL and OBJ. There's a wide variety of models, all free, in such categories as "Industrial", "Fantasy" or even "Music". We'd like to print music! Oh, wait, it's actually musical instruments! Doh!
Via Cadyou (Hat tip to Tom)