Shameless self plug; http://youtube.com/user/Envirotech/
I don't have as much pony stuff on there as of late, mostly been my friends the David Barrett Trio based out of Toronto, Ontario. But! There is a wee bit of pony stuff further back, PMVs, mash-ups, some music I've made related to characters; Rarity, Chrysalis, Applejack too. Look for the playlists that should point one in a better direction. I really would like to get more of my own music on there in a PMV sort of style.
Most of my music is on soundcloud; https://soundcloud.com/enviro_tech03 . I let practically everything be downloadable, I'm never really in it for any money just an expensive hobby and I love trying different genres of music. Note: not for Celestial, because I recorded that with professional musicians I have never made that song downloadable.