"The Hang" is a jam session hosted every Thursday night from 9:30pm-1:00am at LUCID Jazz Lounge in the University District. Regular group plays, then opens it up to additional musicians. I'm posting this to the group as an opportunity for members, even though I don't host it-- the organizer changes from time to time.
When I visited (10/14/2011), the lineup was electric bass, drum kit, guitars, tenor sax, and trombone. No standards were played; instead, a few blues, a couple tunes like Brick House, and improvizations built on bass lines and 4- or 5-chord progressions. Most were in the keys of E and A major, and D minor. Think tunes like Wayne Shorter's Footprints-- that's what was playing. There is no piano in the house; if you play keys you'll need to bring your own portable.