Before upgrading to Snow Leopard I used Deja Vu Sans Mono (a variant of Bitstream Vera Sans Mono) as my Terminal font. I now prefer Menlo, Apple's own variant of Vera Sans Mono, which ships with Mac OS X 10.6. I use 12 pt. Menlo in Terminal and when programming and editing code. A comparison of Menlo and Deja Vu Sans Mono is below (via Jesse Burgheimer on Typophile).
See also: Terminal.app colors in Snow Leopard
