Fonts
Most mudding clients will come with a font pre-set. Often this will be a thin, spidery font, or a blocky, brick-like font. Here is one endeavour to display a good selection of monospace (all the letters the same width) fonts that are easy on the eyes, and suitable for mudding.
TrueType Fonts
Andale Mono
Looks a lot like Monaco. Comes with various versions of Windows or MS Office.
Bitstream Sans Mono & Deja Vu Sans Mono
For most end-user purposes, these two fonts are the same. Free as in software, beer, and speech. Available from here. (The actual difference is that the DejaVu project took the original BitStream fonts and added Unicode characters to them, I think.)
Consolas
Comes with Windows Vista and MS Office 2007(?). Like a version of Courier New that doesn't make your eyes hurt and your spider lustful.
Courier & Courier New
Very light, typewriter-style fonts. Courier New is the default font for ZMUD and CMUD.
Droid Sans Mono
Droid Sans Mono is an Apache-licensed typeface created for the Android mobile platform. Droid Sans Mono can be downloaded from the Android repository (use the 'raw' link next to DroidSansMono.ttf).
Inconsolata
Inconsolata is a popular and free monospace programmer's font. Inspired in part by Consolas, it is modern and crisp.
Lucida Sans Mono
Luxi Mono
This and SimSun are unusual in being monospaced fonts that also have proper serifs (the pointy bits on the ends of letters).
Monaco
Comes with Mac OS X. Looks better in small sizes, and without anti-aliasing.
monofur
Very round. Probably a bit weird for mudding. Available free here.
OCR A & B
This is painful. I don't recommend it.
Orator Std
Proggy Truetype
SimSun
This and Luxi Mono are unusual in being monospaced fonts that also have proper serifs (the pointy bits on the ends of letters).
Bitmap Fonts
Dina
Dina programming font. (TTF version.) Pretty, free. Only comes in a limited selection of sizes, but they're all good.
FixedSys
Default MUSHClient font. Chunky, unpleasant. Comes with Windows.
Proggy
fixednxn
Comes with most Linux distros. There's a Windows package floating around somewhere as well. Some of them are very readable.