When the PI keycap GB was going on, there was some interest in doing a lot of mathematical/scientific symbols and greek letters. There was some support, especially given how popular the PI keys proved to be. I'd pretty much buy any of the math/science ones.
Further suppgestions:
More constants! e, i, omega (expansion of the universe "cosmological costant"), gamma, even tau (though I have always preferred pi to tau).
Symbols: Sigma summations, Capital PI, surface integrals, gradient and "curl" symbols, etc (so you can spell out maxwell's equations across the F# row!)
Anything else?
Alas, none of these ideas has yet gained enough momentum to make it to a GB.
Ideally, they'd be dyesublimated black onto white, but I'd put up with doubleshot if I had to.
Now I'm no good with vector renderings, but wouldn't it be easy to get most of that from a math font or math layout program (what can you get LaTeX to output?) or even the libreoffice math editor.
And, as esoomenona says, it's a good idea to make pictures and post them to the topic for them.
I hope to see GB's for these soon
