Pony.fm is a Brony-specific streaming platform and music archive. I believe any tracks and albums on the site can be streamed for free and downloaded for free. URL patterns are as follows [variables in brackets, examples below]

• tracks (recordings): pony.fm/tracks/[ID]-[track-title]
  • https://pony.fm/tracks/46955-love-is-in-the-air
  • https://pony.fm/tracks/1183-helping-twilight-win-the-crown-delta-brony-remix
  • https://pony.fm/tracks/257-dont-you-dare-let-go-feat-rina-chan
• albums (releases): pony.fm/albums/[ID]-[album-title]
  • https://pony.fm/albums/1496-after-party
  • https://pony.fm/albums/679-sgt-pinkies-lonely-hooves-club-band
  • https://pony.fm/albums/282-wild-fire-ep
• artists/users: pony.fm/[user-name]
  • https://pony.fm/silva-hound
  • https://pony.fm/ditzyrhythm [archived artist]
  • https://pony.fm/yelling-at-cats

note: the [ID] section of these URLs isn't specifically called that anywhere I found, I believe it's a sequential number tho