I currently offer TWO sets of jam tracks for instant download:

 

BLUES HARP JAM TRACKS, Vol. 1  (acoustic)
www.tradebit.com/filedetail.php/2839291-blues-harmonica-jam-tracks-vol-1-zip

BLUES HARMONICA PLAY ALONG SESSIONS, Vol. 1 (electric)
[note:  this set of jam tracks also includes a one-hour video tutorial on how to make the best use of each track]
www.tradebit.com/filedetail.php/4537012-blues-harmonica-play-along-sessions-zip

 

 

If you're interested in the JAZZ side of blues, you may want to purchase a set of jam tracks I recently discovered at PlayJazzNow.com.  They consist of piano, bass, and drums in a relaxed, straight-ahead jazz groove:

SET #3: BASIC JAZZ BLUES
INTERMEDIATE level. Medium swing tempo (mm= 120)
12 tracks, one in each key. Each track is about 4 minutes long.
Price: $12

If your ambitions include transforming yourself into a full-fledged jazz harp player, you'll probably want to visit the PlayJazzNow site and poke around, since they've got lots of other jam track downloads.  Click the link below; it'll take you to the horn player's page.  (You'll also be able to find a free preview of the "basic jazz blues" jam tracks above):

Click here to view more details