[bhouston]

> download these files to a central repository, automatically convert them into a range of usable formats, auto generate an image (like, it appears, Yobi3D has done) and auto generate some meta-data (if none exists) from the page/site the 3D file was found on?

https://Clara.io has the central repository, automatic conversion, image generation, WebGL preview and search capability already. Just no automatic scraping nor automatic-meta data.