DH is a poop, he has a default ringtone. How boring.
My main ring tone is 'AM Radio' by Everclear. I use Jann Arden's "Good Mother" for my parents, Martina McBride's "Happy Girl" for a close girlfriend, and - heh - "Gitchee Gitchee Goo" from Phineas and Ferb for DH.

I don't change them very often though, because I go through FITS to find just the right song and clip.