Key Viewer... Old-time Mac users will remember the Desktop Accessory called Key Caps. Key Caps made it very simple to look up how to get your keyboard to input special characters. Apple dropped Key Caps in Mac OS X 10.2. So, I made Key Viewer.
Apple still ships the Keyboard Viewer as part of OS X, but without Key Caps, there is not a simple method of invoking it. Key Viewer is simply a wrapper around a script that makes it easy to call up the Keyboard Viewer.