Speaking of AI challenges, one just started on monday. Sadly it's hosted in finnish only. There's been many similar no-reward contests throughout the years, lots fun. They make up new game and rules, and let people use whatever programming language they want. You send source code only for the console application, and hoster makes binary of it on Linux test machine. Then they make them play against eachother and count points.

Currently up is: http://www.ohjelmointiputka.net/kilp...nnus=valtapeli
Not sure if google translates the page well, but i'll explain idea shortly. 16x16 board, where players fill 1 empty cell per turn. At the end all solid areas are calculated, and you get exponentially more points the bigger the area is. So 1 big connected area would give most. Other AI/player is only harassing, trying to disconnect the areas of other.