You can't type into the applets at allstarpuzzles.com. They load, but anything requiring key input fails.
1. Install the Java plugin on Mac OS X.
2. Go to http://www.allstarpuzzles.com/cryptogram/02639.html
3. Click on a blank space
4. Press a letter key
---> No character draws. You should see the letter you typed.
Works with Apple's JDK 6.