The term "jam band" is used to categorize a type of music that favors improvisation and musicianship over concise riffs, hooks, and traditional songwriting structure. The term also helps define the fiercely dedicated fans of the music as accurately as it does the bands. Much as with the Grateful Dead -- the progenitors of the jam band scene -- the survival of the scene depends upon a symbiotic relationship with fans. Jam bands nurture a close relationship...