I symlink all the music I care about into Dropbox, which gives me access to the music I listen to most at my office and on the road, but doesn't mean Dropbox hsa to have sufficient space to store ALL of my music. This hybrid works well for me personally.
yeah i store all of my materials for school, including high res versions of all of my textbooks so I can look them up and print things if needed. Also about 2 gb of audio lectures that are not otherwise mirrored online. I wish it had the space to store all my music, but I don't really have the money at the moment for a paid account. someday.