Linux theme... nothing distro-specific, just Linux. There's been Windows and Mac themes, but never one for Linux.
007... N64 style. You can't tell me you didn't lose nights of sleep playing this game.
Family Guy theme, Futurama too.
Sonic the Hedgehog? I don't know, something that just came to me.
I'm a huge fan of R6V2 (Rainbow Six Vegas 2).
Miami Heat or the Kansas City Chiefs.
In lieu of the new one coming out, what about Street Fighter? The original.
I'll post more if more ideas come to me. I'm not creative in the least, but I know what I like, and what I think others might like, but are afraid to ask for.
Edit: X-Men theme? Cartoon style, the old one that used to be on ABC or Fox. We're talking almost 10 years ago here.
Someone else posted it already the idea, but Metal Gear Solid.
Maybe a skateboarding theme.
Mortal Kombat... the first or second. Another game hours of sleep have been lost on.