Zach Weinersmith of the webcomic Saturday Morning Breakfast Cereal has some great ideas to spice up chess. We've seen some clever variants, such as a cylindrical board and a suicide bomber piece. But Weinersmith has made even greater improvements with pieces that behave in very different but not insurmountable ways.
You can view them all here. Gortak the World-Eater is the best of the all.
https://en.wikipedia.org/wiki/Knightmare_Chess