For some reason, sometime around the release of OS X Snow Leopard, Apple made default bold fonts look different. I've been told it had something to do with making screen fonts render more closely to their print counterparts. At any rate, bold fonts on OS X now look terrible by default.

Here's a before/after (the default bold fonts are on the top):

Here's how you can get the "after" look. Pop open your terminal and enter:

defaults -currentHost write -globalDomain AppleFontSmoothing -int 0


The change will take effect when you restart each application (no need to reboot).

To reset them to the original setting:

defaults -currentHost write -globalDomain AppleFontSmoothing -int 2