You remember Font Book, right? That’s the built-in app that OS X offers for organizing and previewing fonts. In Mountain Lion, it gained a feature to make organization a little simpler: Smart Collections.

They work just like Smart Playlists, Smart Folders, and Smart Mailboxes. Option-click the Plus icon at the lower left, or choose File -> New Smart Collection.

Filters in your Smart Collection can include Family Name, Style Name, PostScript name, Languages, and Design Style. That way, you could make a collection that consists of, say, only English, italic, sans-serif fonts.

Source: Mac OSX Hints