File hosting and Song Downloads
I am a big fan of the Choral Public Domain Library. And I would like to see something happen similarly with this, either in hosting Muse Score files on the Choral Public Domain Library or (and preferrably "and") creating an independent site for musicians to post their finished work for free download. I am using this program to write music for my colleigiate a cappella group, and being able to share with others would be a tremendous service.
I believe FInale has a service called "Finale Showcase" which is similar in this regard. Though I am thinking more in regards to the wiki idea. The fact of the matter is that this is a cross platform, and hopefully soon to be (once mac has a full version) almost all OS accessible program. And it is free.
Here is the link for the Choral Public Domain Library: http://www.cpdl.org/wiki/index.php/Main_Page