There are TONS of good blues bands out there. Start out simple...here is a good progression of blues bands and some specific albums to check out:

Robert Johnson
Willie Dixon - I Am the Blues
Muddy Waters - Electric Mud
Howlin' Wolf
Buddy Guy - Sweet Tea or Buddy's Baddest
Lightning Hopkins - Trip On Blues
B.B. King
Eric Clapton
Stevie Ray Vaughan & Double Trouble
Robert Cray

You'd be surprised how much of music, even...ugh...metal, stems from blues. Hope that helped, I'll post more if I think of them.