System Preferences used to allow choosing from two additional text rendering settings, light and strong, in 10.5 and earlier. I've always used the light setting. It's closer to the weight of printed text, but characters still have smoother edges or aren't as pixelated as on Windows.
You can still use the old settings by editing property lists:
defaults write -g AppleFontSmoothing -int 1
sudo defaults write -g AppleFontSmoothing -int 1
The command with sudo modifies
/var/root/Library/Preferences/.GlobalPreferences.plist. It's needed for windows shown by processes owned by root, like the force quit window.
Monospace fonts are often the same width at for example 13 and 14 points, but the smaller size appears lighter or to have more space around the characters:
I've posted a comparison of Cousine, Droid Sans Mono, Inconsolata, PT Mono, and Source Code Pro at Ask Different.