[DeusEx]

How about similar songs/tracks? Not just artists. What Last.fm essentially does is analyze what groups users listen to, and make connections from there, but for individual tracks, it doesn't work as well. Maybe some sort of music-structure analyzing app out there?

 

[Cianyx]

Just try some music forums. For example, since you like classical music, try Classical Music Forums - Talk Classical

They don't talk much about soundtrack but I'm sure you can get great recommendations from there.

 

[buddhashenglong]

Go the old school route and see who else played on the record date, guests, producers, back up vox...