Here's an interesting variant by the inventor of Racing Kings (Vernon Parton). The rules are described here: http://www.chessvariants.org/winning.dir/neutral-king.html
Basically, neither player has a king of their own, but there is a neutral king that may be moved by either player. The object of the game is to checkmate the Neutral King and prevent your opponent from doing so. I don't think there are ANY websites that have it! (Although there is a java applet at pathguy.com where you can play against a computer. But there's nowhere you can play against real opponents.) Brainking could have a world first!
(verberg) Als u op uw beurt aan het wachten bent en niet steeds op F5 wilt blijven drukken kunt u ook de pagina snel automatisch laten vernieuwen door op "Verander" naast "Verversen" te drukken op de Hoofdpagina, en de tijd hier in te stellen op bijvoorbeeld 30 seconden. (Servant) (laat alle tips zien)