I think the answer is to export as Collada (.DAE,) and have the website use the Google O3D plugin. (Manipulation and User Interaction is done via Javascripting.)

Not the expert on this, but it's simple to make a SU plugin that can run other programs, read, and write externally files. SU can communicate with the outside world in this way. There are probably more sophisticated ways that others might be able to point out.