Sketchucation - Sketchucation is a 3D SketchUp Community for students, professionals, designers, and hobbyists.
CGTips - CGTips is a 3D Architectural Visualization learning platform for Architects or interior designers to build their skills in an interactive way.
3dxo.com - 3dxo.com is a great place for both professionals and hobbyists to find some really cool, free 3D models.
TheSketchupEssentials - TheSketchupEssentials is a community to get SkethuUp tutorials and help from professionals.
Tiling Textures - TilingTextures.com is a growing library of free tiling textures or known as seamless textures.
Texture Haven - High-quality PBR textures for free to everyone, with no catch.