Sometimes XSS is far too amusing. I had this one sent to me by (name withheld). The site CISSP.com is vulnerable to a cross site scripting attack. This may be a dated one but, it still works and I had to admit it is funny.
The example code (removed on sober second thought). (be aware that this will launch the XSS)
Here is a screen cap for your enjoyment.
Enjoy.
[tags]CISSP.com XSS, Funny XSS, XSS[/tags]