I'm a phish fan. I can really dig into some jam music sometimes and phish is one of the better "jam bands" out there. If you don't know any of their songs, here's some of my faves you should check out:

Waste
Wading in the Velvet Sea
Bouncing Around the Room
Stash
Heavy Things
Funky Bitch (w/ Son Seals)

I could name more, but you can get a rough essence of the band from these songs.