Alright, this might not work, but I figure it's just an idea so I'll share it with ya ;)

Embedding.
Much like youtube does, you can grab the embed code and place it on any site.

It'd be cool if we could do a similar thing for the songs here. The embed code could automatically add a subtext/link to this site.

You'd reach two things with this:
* more spreading of the awesome classics
* near-free linkbacks to this site = more users

The main drawback would be more bandwidth usage however.