Poly by Google is a library of free 3D objects for augmented and virtual reality apps.
threed.io is a browser based tool to generate custom device mockups on the fly. Upload your Designs, make adjustments and download your custom mockup! Even works pretty nice on mobile. We're still in beta, but if you're interested in threed, please read the about text on the site.
Patches is a visual programming editor for building WebVR and WebGL experiences. With over 350 patches, ranging from low level programming, loops, variables and arrays to colour pickers and interaction triggers, Patches is a powerful and flexible modular system for building complex webVR projects.