My Suggestion:
If the song is part of a beatmap pack, display the pack name (With potential download link) on the song page.
EG:
http://osu.ppy.sh/s/46404
This would assist in informing newer users about the presence of beat-map packs, as well as allow existing users to find similar-style songs.
This would also help reduce the amount of "You're downloading too much - Please wait 2 minutes!" by letting the user download the entire beat-map pack on the separate site (During the next played song, or some such), letting them grow their song collection more quickly, as well as having more commonly played songs.
If the song is part of a beatmap pack, display the pack name (With potential download link) on the song page.
EG:
http://osu.ppy.sh/s/46404
This would assist in informing newer users about the presence of beat-map packs, as well as allow existing users to find similar-style songs.
This would also help reduce the amount of "You're downloading too much - Please wait 2 minutes!" by letting the user download the entire beat-map pack on the separate site (During the next played song, or some such), letting them grow their song collection more quickly, as well as having more commonly played songs.