Here's a few music related "illusions" that I thought you guys might have fun with.
http://www.moillusions.com/2006/10/aphex-twins-devil-face-illusion.html
http://www.moillusions.com/2006/04/virgin-digital-find-75-bands-illusion.html
http://www.moillusions.com/2006/10/andrew-golds-32-wrong-things.html
You may also want to check out the "audio illusions" category on this site. Beware, you could spend all day on this site, just hitting the "next random illusion" button!!!
http://www.moillusions.com/2006/10/aphex-twins-devil-face-illusion.html
http://www.moillusions.com/2006/04/virgin-digital-find-75-bands-illusion.html
http://www.moillusions.com/2006/10/andrew-golds-32-wrong-things.html
You may also want to check out the "audio illusions" category on this site. Beware, you could spend all day on this site, just hitting the "next random illusion" button!!!