I dont like many of the bands in that 'genre' either...Grateful Dead, Allmans, and Govt Mule is about it...
Im guessing the reason why I 'like jam bands' is because Ive been to the Bonnaroo fest the last 2 years...where Ive seen such great 'jam bands' as De La Soul, Matisyahu, Lake Trout, Primus, J5, X-ecutioners, Saul Williams, etc...