TTFs can be "imported" on user end just by installing the needed font on the system. It basically would work the same as if we'd let them import those to bizhawk only, since both ways allow calling them by family name from lua, but global install sounds smarter to me. So I limited this to 2 main fonts everyone is used to, but there's still a ton of good pixelated fonts already:
http://fontstruct.com/gallery/category/1/pixel_optimized
BTW, creating a bitmap font using
http://www.angelcode.com/products/bmfont/ can be done with any font that's locally installed, so there's really no limit for bitmap ones either. They even have a benefit of being able to support halo and stuff. But they are really slow, 20 lines of text and my emulator slows down below 100% speed. But since you can't import them to a compiled executable, here's where that option would really help.