For those feeling adventurous: Input[1] is a proportional font made for coding. It's also highly customizable.
(Edit: typos.)
Too bad it doesn't include programmer ligatures, I've been looking for a proportional font that included those (I tried hacking them in myself but couldn't figure out the font hacking tool chain).
I consider myself fairly adventurous, but this is clearly beyond my comfort zone :)
I'm not adventurous enough for proportional fonts, but the monospaced Input looks quite nice. And I'd not heard of it before. I'll definitely give it a spin.