What is the standard programming font used in Textmate?

Monaco.

It is downloadable for Windows here (Direct link: http://www.webdevkungfu.com/files/MONACO.TTF)

I believe it's Monaco 12 pt.

If you'd like to use the same font on Linux, you can by following the instructions on this blog: http://jorrel.blogspot.com/2007/11/monaco-on-ubuntu.html

This isn't exactly an answer, but you might also want to check out Anonymous Pro. I've tried a lot of programming fonts over the years, and I have never found another one nearly as readable. (I know the link path says "font sales", but the font is free and licensed under the SIL Open Font License.)