I found an XSS vulnerability in http://eenmiljardseconden.frankdeboosere.be/ . This vulnerability was possible due to invalid input validation/bad programming. The owner was contacted and a satiric fix was deployed.
(media stunt of Flemish television weather forecast presentator)
After entering a message on the "Stuur een bericht naar de toekomst"-page, you are presented an unique number of your request, to track it. You were then redirected to http://eenmiljardseconden.frankdeboosere.be/messagesent/id/[number of your request]. The number could be replaced by any value to inject content into the page.
It is now solved, and if you try to execute it again, you get a link to Rick Astley's "Never gonna give you up" on YT.
2012-05-29 - discovery and owner notification.
2012-05-30 - Fix
2012-05-31 - Disclosure at 42(at)discuss.hackerspaces.be mailinglist.