Check out Artist's Share:

'A place where fans fund the projects of their favorite artists in exchange for the privilege of "participating" in the creative process.'

One of the features that you "Jazz Workshopers" should be interested in is the "online lesson" component.  The artists regularly submit these lessons in conjunction with the music they're most recently recording.

Some of the artist's featured are:

And more.

It's a pretty awesome concept, and free to join.