I started to compile links to websites where free 3D models can be found. If you know other good websites, feal free to post them in the comments :-)
Static models and scenes:
- Great collection of models for scientific publications on Morgan McGuire webpage: http://graphics.cs.williams.edu/data/meshes.xml
- 3D Render challenge: http://www.3drender.com/challenges/
- Crytek: http://www.crytek.com/cryengine/cryengine3/downloads
- Keenan Crane : http://www.cs.caltech.edu/~keenan/models.html
- Sibenik model: http://hdri.cgtechniques.com/~sibenik2/download/
- AIM@Shape : http://shapes.aimatshape.net/
- Characters Creative Common: http://artist-3d.com/
- Characters: http://www.3dvalley.com/3d-models/characters
- Blender files: http://www.blendswap.com/3D-models/category/featured/
- Archive 3D: http://archive3d.net/
Animated models and scenes:
- Ingo Wald: http://www.sci.utah.edu/~wald/animrep/
- MIT CSAIL 1: http://people.csail.mit.edu/drdaniel/mesh_animation/index.html
- MIT CSAIL 2: http://people.csail.mit.edu/drdaniel/dynamic_shape/index.html
- MIT Animals and Face: http://people.csail.mit.edu/sumner/research/deftransfer/data.html
- Face data: http://grail.cs.washington.edu/software-data/stfaces/index.html
- Pants: http://www.ryanmwhite.com/research/cloth_cap.html