My new favourite Steampunk music discovery is Moth, a band from the UK.
Here’s a video for the song Tree Snow. The music is vaguely gothy minor key pop rock with a lovely chorus hook and even a proper pop song key change at one point. The video is all quirky steam-powered robot fun.
They have a (rather confusing flash driven) website, and can be found on CDbaby. Definitely worth a listen to.