The 5k competion was "an award for excellence in web design and production". The idea was to pack as much webpage as possible into 5k or less including all associated assets. It ran from 2000 to 2002.
In 2001 I entered "Apparently Random, Totally Predictable", a javascript implementation of a cellular automata. It was judged to be one of the finalists in that years competition.
Since then the contest website has gone offline, but some info is still available: