Agree. ExploreMusic.com is a gem. I can see it now as one of those TV ads for a set of classical DVDs like Readers Digest etc. have done before. "Explore the World of Music in this limited edition set, not available in stores..."
There are many ways to start developing this. You could look at an affiliate for sheet music; a forum for musicians, beginners' classes for guitar etc., -- endless possibilities and a definite keeper! Well done.