Here at UBEST headquarters, we have experimented with a vidiscript-based “Virtual Studio” for enabling online musical collaborations. This setup should allow users to share and comment upon audio or video files, perhaps representing works in progress, while giving them the option of blocking access by random members of the general public.
But what if you just want to draft some sheet music without making a recording? Then Noteflight may meet your needs quite well. I tried it yesterday and was impressed by its ease of use … and by the fact that it’s free! (There’s also a “premium” version available for $49.)
Among other attractive features, registered users can easily share their scores with unregistered people; each score has a unique URL. Also even though preparation of the scores is web-based, and printing web pages can often be a challenge, my sample score snippet looked fine when I printed it out.