JC's Music Session directories
This is John Chambers' directory for experimenting with idas for online "session" music.
Most of the music here is linked in from other directories for a specific kind of music.
The basic criterion here is that the tunes should be "active" or "basic repertoire"
for the sort of sessions named by the directory.
But the whole topic is somewhat vaguely defined,
and this should be treated as a learning experience.