Lately, I have been downloading podcasts such as Jazz Insights, by Dr. Gordon Vernick, of Georgia State University:
http://www.music.gsu.edu/directory.aspx?Id=81 I play these in my car while driving, though my iPhone.
Not technique oriented, but very interesting, and can be instructive as far as music construction goes. The cool jazz podcasts covering Miles, Coltrane and others in the late 50s through 60s, and the changes that were occurring, how each of the different artists approaches differ ( like Miles Davis as compared with Coltrane as opposed to Cannonball on "So What") and that helps me to understand different ways to approach melody, etc. I get these free from iTunes U.
The "Kind of Blue" series of podcasts, 4 in all, are among my favorites so far.
I also downloaded a series of music theory podcasts from iTunes U, though honestly, most have been over my head, and a little dry to listen to. I am going to go back to them next road trip, and see if I can muddle through some more though.
These things are free too! Very cool.