I am hugely anal about this topic and I've tried all fonts mentioned at the time of this post. In the end, Consolas has racked up the most miles during my coding and Proggy Tiny for the output console (allows you to fit quite a lot). Don't get me started on color theme.
I would humbly suggest trying either MonteCarlo [1] or its derivative, Tamsyn [2]. Certain characters (like the "@" symbol) look much better in either of these fonts.
