Damaged Fonts -- Lloyd Lim <email@example.com> says that a good check for bad font files, along with other files with resource forks, is to run John Norstad's excellent virus fighter, Disinfectant (now at version 3.2, see below), which checks for and reports damaged resource forks. It may not catch all types of damage, but it is a useful troubleshooting tool.
Two Shortcuts for App Exposé
If you want to see all the windows for a particular app via App Exposé, there are two hidden shortcuts. For either, start by pressing Command-Tab to bring up the app switcher. Then, while still holding down the Command key, press either the 1 key or the up arrow. That puts you into App Expose mode, with all of an app's windows showing, and recent documents in a row across the bottom of the screen. Let up on the Command key, and then you can press Tab to cycle through all the running apps.