Here's a list of the ones I know about:

Sundays:

Simo's Café (Valley Junction) 6:30 - 9 or so.

I believe there is also one at the Main Gate (across from the fair grounds) that night.

Tuesdays:

Billy Joe's Lounge in West Des Moines - 7-9 (or 10)

Wednesdays:

Des Moines Underground (haven't been to it)

Thursdays:

Des Moines Social Club - 7-10 every thursday.
Blues on Grand (charges cover).


1st Thursday:
Corey's Irish Pub (Bondurant) 7-12

2nd Thursday:
Ritual Café 7-9

3rd Thursday:
AJ's on east Court 7-10