Apple Keyboards

rentzsch.com: Pulling a Double Shift:

"If you have a last-generation PowerBook or a MacBook Pro, here's some weirdness for you to try out:

• Fire up TextEdit.
• Press the Q key. A lowercase 'q' results.
• Press and hold the left shift key and press the Q key. An uppercase 'Q' results.
• Here's were it gets weird. Press and hold both shift keys and press the Q key. Nothing happens.

In fact, when you hold down both shift keys, a bunch of keys go dead. Function keys F1 through F9 become non-responsive."

I have confirmed this particular weirdness and it happens in other applications as well.