Hi,
There is a very very nice feature (or possibly quirk?) to the text library that SubEthaEdit and BBEdit are built on. When you adjust the font size for Monaco down to "9" then it loses its fuzziness and "snaps" into pixel-perfect, fixed-width readability. I don't know why this happens but TextMate doesn't do it. If I turn font smoothing off for size 9 and lower, TextMate makes Monaco pixelated and crisper, but it does not look fixed-width (i.e. it's slightly squished together for some letters and not very easy to read).
Which version of TextMate do you use? There was some changes in the font rendering in version 1.0.1b1 and 1.0.1b2 so if you are using TextMate 1.0 or 1.0.1b1, you should maybe try with the latest beta.
Vincent Isambart