Voice Candy is a fun and useful recorder for the Apple Mac.
It allows you to add fun effects to your recorded voice.
You get 8 different effects to play with. You can switch the effects while recording for some extra fun. For example, record a conversation between Darth Vader and chipmunk to produce something that just seems wrong.
This would be an ideal addition to your normal recording software to produce fun Podcasts with your pupils.

http://www.potionfactory.com/voicecandy/
Voice Candy requires
Mac OS X 10.4
G4 or faster processor
$12.95 (£6.90)