You have my permission to modify and publish changes to the themes I previously published for gigabeat.
4Car, Ajant Orange, Green5g_4_GB, Slant, Stele
Don't publish the Rockamp Black, White and Blue as they were removed from the wiki as copyright risks.
Twins-territory wasn't previously published on the gallery wiki because I wasn't sure it would be allowed because of the Minnesota Twins Baseball logo, so probably don't publish that one either. (Cool another Twins fan!)
Feel free to modify for your own use though.
I might go back and update what I have out there, I've been working on other projects the last year and haven't been keeping up with the changes to rockbox. I think I'm still running a 2007 build on my player...