CoDesign says Do You Code? You Should Try This Font "Monoid is a new programming typeface designed to be clean, uniform, and precise, just like good code."
"Programmers want a font that is clean, uniform, highly readable, and precise, just like good code. Monoid is a new font designed by Andreas Larsen that aims to do all the above, and more. An open-source font aimed at coders, Monoid has been designed, first and foremost, to be highly readable even when you're scanning through ten thousand of lines of C++, looking for that one bug-causing typo."
It's open source (so free) and you can download it here. At the bottom you can preview the font and choose from a few alternatives. I like the alternate 1 better. Note, the alternative preview doesn't work in Safari.