Pangram Validator started as an AppleScript. Later, I developed a version in Macromedia Director so that I could share it on the internet.
Pangrams are phrases that contain every letter of the alphabet. The most famous English pangram goes "The quick brown fox jumps over the lazy dog."
The validator checks any phrase you type and tells you whether or not you have typed a valid pangram. If not, it tells you what letter(s) you need to shoehorn into the phrase. Useful for type designers; fun for everybody else.
The AppleScript version of Pangram Validator was chosen Script of the Week by MacScripter.net (when it was called bbs.applescript.net). Pangram Validator was chosen because it's lots of fun, in addition to being "a great demonstration of Applescript's power and versatility," according to award administrator Gregory Spence.

The opening screen shows an example pangram. The user types in the text entry field.

When the user clicks the Validate button, the application displays any and all missing letters. This is an incomplete pangram.

This shows a complete pangram.

The information button reveals information about pangrams and the application.
Click here to try it out. Requires Adobe Shockwave.