This link is example only, we may create repository viewer for us, it is pretty handy when You want to see some work or searching something, but... (there is always some but) all files should have preview model in .obj and .mtl (if You want to see texture).
We may create git repository with 3 main branches, like: final, development, test. Users who want to contribute may fork it, place their changes push to forked repo, and send pull request, than developer may be able to see what is pushed, deleted etc ...
Some rules should exists, for example someone who is pushing something need to keep such dir structure:
some_model
|- preview
|- icon.png (like those in inventory)
|- preview.jpg (model in all rotations if exists, zoomed on 400% and 100% and render)
|- model.obj (for 3d preview only)
|- model.mtl (for 3d preview only)
|- texture.gfx (for 3d preview only)
|- description.txt (prefer some formating text like textile or similar)
|- source
|- some 3ds, obj, c4d, or other formats
|- psd and similar
|- rigged (optional)
|- model.fo3d
|- model.x
|- texture.gfx
|- not_rigged (optional)
|- model.x
|- texture.gfx
We may also use some free tracker, where we may be able to create tickets like "we need x model of x", "model y texturing", so people who contribute may be able to take such ticket and push ready solution. Git allows to many nice operations of repo. Browsing may be done via www and You see all info user placed, commit message, icon and preview, when You click 3D button You will see 3D preview. Also we are able to keep in this repo tutorials, documentation and many more, all who want to contribute just need free github account, after pull request any developer may merge it or reject it (or even just ignore).
That's my suggestion, I can prepare it if You want.