I'm a big music buff, so I'm usually listening to one band or another. I've found this really helps me with writing as well.
Several bands inspired me while writing Cassastar.
In Flames is great for the action and fight scenes. "System" and "Could Connected" possess so much energy! The band's aggression really helps, too. Guilt Machine's "Green and Cream" fits well with the space battles. I can really see the characters in their fighters, blasting away!
Redemption and Dream Theater are great for scenes where the characters interact. Really sets the mood for more dramatic moments.
I've heard other authors and writers say music inspires them. So tell me! What music inspires YOU?