I recently got an iPod, so I went searching for giant monster music on iTunes. It was a quick search, but I came up with a few things, besides soundtracks.
First of all, there is a surf rock/metal band called Daikaiju. I've been aware of them for a little while now and they seemed like great fun. I downloaded two songs from their self-titled album: "Super X-9" and "Daikaiju Die!" It's great stuff. The band is kind of interesting too. They wear kabuki masks and all their press materials sounds like words translated from Japanese by an Internet translator.
The second thing I found was a podcast by Infinite Sector Collective.
The infinite sector is a non-profit collective and netlabel dedicated to sharing and promoting free experimental music, noise, and electronica. Our members include musicians, bands, and artists from all corners of the globe.In honor of 50 years of Godzilla, their first podcast episode is dedicated to kaiju eiga. So members of the collective do songs about Rodan, Hedorah, Biollante and others. Most of it is very experimental. If you like static and Metal Machine Music, you might like this. I like a lot of weird music, and I had a tough time with most of the songs. The song "Jet Jaguar," however, was more approachable than the rest of it. It was performed by the group Terminal Shock. The podcast is not for everyone, and clearly not intended to be, but check it out and see what it does for your ears.
I gave a search on iTunes for "kaiju" and came up with "Kaiju Babylon." It's a song by jazz guitarist Henry Kaiser. Like Infinite Sector Collective, it's experimental music, but I found it more fun. It was like some twisted combination of Sonny Sharrock and Spike Jones. I was happy to find Kaiser because I notice he has connections to other artists I like, such as Captain Beefheart, Richard Thompson, Sharrock, Bill Frisell and John Zorn, among others. And, apparently, he is a fan of giant monsters. He gives his praise to "Gamera: The Revenge of Iris" at his journal. (That just shows he has taste as well.)
Finally, something I didn't find on iTunes, but wanted to mention: King Geedorah, "Take Me to Your Leader." King Geedorah is actually MF Doom, an underground hip hop artist who has gotten much praise for his purist stylings. The album is a lot of fun and can be enjoyed even by non-rap fans. Quite a few of the songs on the album are "instrumentals" made up of sounds and clips from giant monster movies. If you do like rap, there's some great work on the album as well. Some well known rappers are here, but hidden under giant monster pseudonyms. I recommend it.
While I'm at it, I'd like to remind everybody about The Monster Project, who I wrote about here.