It would be great to have an either self hosted or embeddable interactive 3D model viewer that can show STL or STEP files (typical CAD formats).
- easy import/export from 3D CAD software into the viewer (not requiring manual texture & lightmap baking)
- proper light setup and implemented self shadowing of models, otherwise its really hard to see the 3D nature of a part
- WebGL, to prevent dependency on uncommon plugins on user side (flash, unity3d, etc.) - should be as widely supported out of the box as possible
- has to work without the viewing user being required to register an account anywhere