I'm sorry but ummm..... I don't quite understand this topic.... Are you guys saying that you want to have a 3rd party site for someone keeping an eye out for criminals stealing copyrighted material? Or are you wanting a site for just putting up models to be used only for MakeHuman models? or ???
if anyone wants to sell their 3D models there is always TurboSquid ( the only popular place that i know of where you can sell your 3D assets, feel free tomention any others you know of ).
From my perspective: If someone were to build a brand new site tohost 3D models/textures/animations/other_assets for MakeHuman character models then why not just post them here on the MakeHuman forums in a .zip file and then explain what license restrictions you want to place on them. "Legally" you could just refer a court/judge back to the MakeHuman site and to your specific post showcasing that you previously created and posted your assets and under a specific license which went up at a specific date/time. <-- that would all "pre"-date anyone downloading or copying your work which would be all the "proof" you would need to proove that someone either outright stole your work and/or is in violation of your license for the work.
^---- all that would need to be done to make that work is to "lock" a sub-forum on these MakeHuman forums that would _not-allow_ any post/topic editing by anyone other than an administrator.
^---- poor-man's copyright.. Done.. in my humble opinion
--PLUS-- This would help bring in more traffic to MakeHuman as you could spread the word about your assets and people would get excited knowing that they too can create their own assets.
@Manuel: if this sounds like a good idea then how about creating a new sub-forum for "Third-Party Art Assets ( no post editing allowed here )" ?