If you click through to the screendump of the bids there are some pretty obscure jokes besides the obvious KurtG and GeorgeCantor. BusyBeaver is another computability joke, solving "in the most productive manner possible". chn's bid is in infinite-radix numbers. The HaltLib.NET library is claimed to work in PNG and BNF among other languages. J. S. Carberry is a mythical Brown professor started as a practical joke in 1929; the backstory is interesting: http://students.brown.edu/College_Hill_Independent/?p=2127