Let me rephrase, can they be used as a way to file data (and data will mean websites, movies, music, etc)? For example, instead of hosting a lot of files on your domain (high bandwidth costs) can you create subdomains that will redirect to the content to an unrelated party. For example http://domain.com/forums/music versus http://music.forums.domain.com.

A working example would be http://whois.dweezel.info/ which redirects to my online resume.