I teach music tech and digital audio at the University level and have never had much use for iTunes, as it seems to me to be designed mainly for teenagers' CD collections. But a colleague showed me this trick, and I was so floored I had to repeat it before I'd believe it.
As everyone knows, MIDI is not sound, but instructions for playback of sound. The actual sound is generated by the local synth (which makes MIDI a good choice for internet music). If you burn a MIDI file to CD, it's just data and can't be played on a CD player. You have to send the playback to a synth, record the synth in a digital editor and burn those files to create actual music files.
But create a playlist in iTunes with MIDI files, then burn that to CD and it burns audio files that can be played back on a CD player. I'm guessing it converts the QuickTime synth sounds in real time while burning. Not even ProTools has a similar feature. Pretty slick.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040824211827667