This address held the mad scientist's secret laboratory, where Fredrik Lundh put experiments that were not quite products. It is linked from a handful of places that have been pointing here since the nineties, including the W3C.
His experiments are not reproduced here. They are in the Internet Archive along with the rest of the old site.
In the same spirit, small things that run in a browser and are useful rather than finished products:
All of them run on your own machine. Nothing you open is uploaded.