I had recently read a post entitled “Top 10 Programming Fonts”, via Daring Fireball. I figured I would try out the number one font, Inconsolata, for Java editing in Eclipse. Instant problem: I had never installed a new font in OS X before, and had no idea how.
I hit the Quicksilver hotkey and typed ‘font’—the first match was Font Book, and that looked promising. I downloaded Inconsolata in Open Type format, selected File > Add Fonts... in Font Book, and pointed the dialog at the downloaded Open Type file. Done.
By default, the font is installed for the current user only, but there's a preference to allow installing a new system-wide font. Back over in Eclipse, Inconsolata now shows up in the font selection dialog. I'm currently trying it out. Initial impression: looks nice.