What strange chess rules can you think up?

I'm feeling it!  I will contribute 1000 flyers and post them onto tellie polls!

My version, played only by me and my club, is Ghost Chess.

In this version, you can select two pieces, as long as they are not kings, queens, or pawns, to be Ghosts. Ghosts cannot be captured or capture and can only move as the original pieces can. A ghost cannot end a move on the rim of the board (unless that's it's starting position). Ghosts can move through all pieces except for other ghosts and cannot check. A ghost only becomes effective when pieces are taken, as then they can move through the piece and "possess" the piece. This piece is converted to the possesser's color IF the possessee is the same as a piece that was taken by the possesse's color. Ghosts cannot end their turn on another piece.

kung fu chess: no turns, just play as fast as you can!

That sounds interesting actually... simple but interesting. I'm sort of surprised that no one has said anything similar so far.

Good luck grasshopper!

The king can only mive in a certain box (from Chinese chess)

I haven't read any of this thread yet, so please forgive me if somebody else mentioned this already, but my suggestion is that once per game, after the opponent makes their move, one may undo their move, and the opponent must choose and play a different move instead. This option may not be exercised when the opponent has only one legal move, but it's fine if there are only two legal moves, as long as one hasn't used the single opportunity already.

This rule will allow you to reduce the effect of a mistake you made in some cases, but more importantly, it gives each player more rope to hang the opponent with, as now one also has to be wary of (and try to trick the opponent into) positions where there is only one decent reply and all the others are bad. This will also rule out some theory lines with lots of only moves, unless there are no other legal moves or the opponent has already used their one opportunity to force a different choice.

If a pawn goes on the 8th rank, and it promotes to a Queen, if the new Queen goes on a8, a1, h1, h8 she can promote into a king, and then your oponnent has to checkmate both of your kings, and if he does it you have to give him a trophy !

If in at tournament you play on the first round at the 1st board, and you remain here for 3 rounds, you automatically get 10% of the fees !

If more than 3 queens for each side appear on the board, the first one who gives check wins !

If someone has the bishop pair, his oponnent has to give him 10$ every 10 moves. But if he loses on bishop, he gives back all the money +10 $

Already been done:

http://play.svenardo.com/chess/

So Many ideas for new, apparently at least, "semi-serious" rules.  Wow. All you guys must have mastered the "old" game so well that you're getting bored with it.  Me, I guess I'm lucky, since I can't Possibly live long enough to get so good at the "old" game that it starts to bore me. 

Intresting !!

At any point in the game - unless the King is in check - the royal power can be transferred from the King to the Bishop. The Bishop is henceforth known as the Pope, and the new objective of the game is to checkmate the Pope. The King becomes just another piece. Also, there can only be one Pope on the board at any time.

It's maybe not so usefull, but since modern chess is based on European medieval society, it should include the Pope.

What if the King defies the new Pope by starting his own church so he can divorce the Queen and get a new one?

That's been done already; bughouse.

How about force capture like in checkers?

A queen can jump over pawns

Before you start a game, you must bang the table. Any piece that is your opponent's that falls down is captured. However, if one of your pieces fall down, you must play without it OR eat 15 cans of Lima beans