This article describes free and paying CAD model collections to speed up projects.
Free
- http://www.3dcontentcentral.com
- http://www.archive3d.net/
- http://www.3dmodelfree.com/
- http://www.traceparts.com/
- http://3dxtras.com/
- http://artist-3d.com/
- http://portal-en.partcommunity.com/
- Google Warehouse
- Youtube (not a model collection, but some animations are made from existing models, can thus be requested on author)