Hmm sounds fair enough, however I don't think the content would need to be hosted by you.
The thing is, on that Garry's Mod game I mentioned, say if I wanted to set up a server and I wanted to have a car on it that no-one else would have (say for instance I made it myself), I add that car to my server's "addon" folder and anyone who joins my server will be download that file straight from my server. I think that may be the easiest way as I'm not sure if every server owner would manually upload each model they have to a file-sharing website or their own. Plus with the likelihood of bad/dead links it may be rather annoying.
Also, if other players on a server have their own models, maybe every other player on the server can download the files, that way it wouldn't be as tasking on the host's end and the uploading and downloading would be spread between the players.
Basically my point is, it might be easier to have some sort of models folder for each individual and the files they put in there will be given out to every other player in the server, that way there is no trouble of going to external websites and downloading 1000's of files. Also, the only stress on internet connection is shared between players, not solely dumped on you.