From Insider Software:
Smasher preserves the health of your applications by performing automatic maintenance on your Mac. It works unattended to eliminate corruption to font caches and temporary files, the number one cause of font-related problems and workflow interruptions--so your fonts always image correctly. Smasher's set-it-and-forget-it functionality eliminates cache-related problems on an automatic, ongoing basis. Like a virus checker, it runs regularly to clean and maintain the integrity of your Macintosh and ensure that you start with pristine font, print and preference caches every time you use your Mac. In doing so, Smasher can eliminate common font problems including incorrect font menus, garbled text, faulty font substitutions, false font corruption warnings, and application instability and performance problems.