Here is a compiled list of 3d print resources.

Another page kept up to date by Royce Barber can be found at http://ontu.org/node/145

www.yeggi.com
www.thingiverse.com
www.grabcad.com
www.tinkercad.com/things
www.cgtrader.com
www.forge.zheng3.com
www.stlfinder.com
www.trinpy.com
www.digible.net
www.sketchfab.com
www.shapeways.com
www.yobi3d.com
www.youmagine.com
www.turbosquid.com
www.cults3d.com
www.3dwarehouse.sketchup.com
www.pinshape.com
www.myminifactory.com
www.3dcadbrowser.com
www.123dapp.com/gallery/content/all
www.libre3d.com
www.3dshook.com
www.3dexport.com (www.3dexport.com/free-3d-models)
www.tf3dm.com
www.treatstock.com/3d-printable-models
www.open3dmodel.com
www.3dcadbrowser.com
www.archive3d.net
www.3dcontentcentral.com
www.shapetizer.com

Source :

Daniel Halvorson, Royce Barber