Have you ever made a playlist you wanted to burn to an audio CD, but it was a couple of seconds longer than 80 minutes? If you have, you might have noticed that iTunes will want to burn two CDs to make up for a couple seconds.
If this happens to you, try burning the same playlist from the free LiquidCD instead. It will let you burn it, many times. I don't know exactly how much more information or seconds it allows, but it does the job for about 20 seconds more.
LiquidCD also allowed me to burn an AVI that Toast didn't because of the size, so you might also try this tip for data.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060819213900770