Shapefest - A massive library of 3D shapes for everything!
Womp - 3D Made Easy
Wannathis - 3d illustrations and freebies
Tool Print - From Design to Doorstep: Swift and Simplified 3D Printing.
Craftwork - A collection of User Interface resources made by Craftwork
AstroPrint - Slice, Store, and Print your 3D files from any web enabled device.