My new favorite typeface for programming is Consolas, a font designed for use with Microsoft Visual Studio 2005. I use it there, but I now also use it for SAS programming.
It uses ClearType technology, so the "crisp and clean" benefits kick in only when you have ClearType smoothing enabled. It makes my eyes feel younger. The font is usable on Windows XP and Vista, where ClearType is available.
(Side note: "consolas" is Spanish for "consoles". My programs have taken on a more latin flavor already.)