Kernagic by Øyvind Kolås is a standalone software tool that can automatically letterspace a UFO font. It implements several different letterspacing approaches:
- LetterModel by Frank E. Blokland
- Snap Gap, which snaps "rhythm points" of glyphs to a desired grid
- Interactivos Average, a simple approach expressed in https://gitorious.org/libregraphicsmag/interactivosbook .
Note that the Average method was dropped from later Kernagic releases, as it did not produce results as satisfactory as the other methods. It is mentioned here for the sake of completeness.