Visual Hunt - We hunt free high quality stock photos.
Sketchucation - Sketchucation is a 3D SketchUp Community for students, professionals, designers, and hobbyists.
Pixabay - Over 270,000 free photos, vectors and art illustrations
3dxo.com - 3dxo.com is a great place for both professionals and hobbyists to find some really cool, free 3D models.
Yay Images - Get unlimited stock video & image downloads.
Poly Haven - Poly Haven (formerly known as Texture Haven) is an online website where you will find scanned textures without any cost and that are of high quality.