quuz is to quux what baz is to bar. In other words: Nothing much at all. This domain was registered with the intent to create a playground for projects which do not really fit anywhere else. I would have put them on annevankesteren.nl if the hosting conditions for that domain were better at that time.
quuz can also be seen as a mistyped metasyntactic variable of which the correct spelling is quux. However, this is a much less interesting point of view and is therefore strongly discouraged.
quuz used to host the Live WebVTT Validator and Live URL Viewer. Now it hosts redirects for them.