The original topic for this one was "flip", but I didn't quite make it that far. The very first topic we implemented was "polar", for which I made a neat little board game I called "Polar Bear Hop". I made a few homemade Polar Bear Hop game boards and handed them out for Christmas a few years ago and posted instructions here.
One part of the game is "flipping" an iceberg over to your color when your polar bear lands on one of your opponent's icebergs. So, I thought I could make an online version with some graphical "flipping" when this happened. I didn't get to the graphical part, but I did get most of the rules implemented and a very simple AI computer opponent. Play Polar Bear Hop.