Is there a way to know what fonts will work together? Building a palette is an intuitive process, but expanding a typographic duet to three, four, or even five voices can be daunting. Here are four tips for navigating the typographic ocean, all built around H&FJ's Highly Scientific First Principle of Combining Fonts: keep one thing consistent, and let one thing vary.
via Ask H&FJ: Four Ways to Mix Fonts. An awesome resource for the print designers out there or the web designer willing to use custom fonts.