Lee's Unleaded Blues is a kickin' jazz n' blues joint in Chicago. If you wanna hear real Chicago style blues, you gotta go here. The bands are always super soulful and keepin' it real. Also, the crowd is always really into the music.
If you're a musician, be sure to get to the jam session. The times are somewhat sporadic, so be sure to check out their music calendar. This is a great place to meet really good musicians. If nothing else, you can learn a bunch just by listening and asking questions.