In much the same that pasting a Wikipedia or Amazon URL will cause some javascript-type-magic to take place that auto-selects the relevant AR and clean up the URL, I'd like this to happen with Spotify URLs (and maybe their URIs) and the "Can be streamed for free" AR.

Track URLs look like:
http://open.spotify.com/track/7gwRSZ0EmGWa697ZrE58GA

Album URLs look like:
http://open.spotify.com/album/1FpzNqDbugk77xUj0qOrtQ

Artist URLs look like:
http://open.spotify.com/artist/293zczrfYafIItmnmM3coR

Spotify also has URIs. These look like spotify:track:7gwRSZ0EmGWa697ZrE58GA and similarly for albums and artists.