tonyh: If there is a chance to win resigning should not be "forced" with doubling. I agree that sometimes the games drag on pointlessly when other side has no chance whatsoever. But determining when a game is decided is not that easy on many games. If doubling was there many endgame turnarounds wouldn't happen. For example in a game of reversi 10x10 my situation looked really hopeless after move 36 (and even before that). I was thinking about resigning and surely my opponent would have doubled at that point if the option would have been there. Then resigning would have been the only sensible option for me to do. However i continued to play and managed to clinch victory with a few points margin! It was a great match and it would never have happened if doubling was there. Many such games where other side has definite advantage would end prematurely if we could double. Here's link to the game.

But gammons are a different thing. The doubling cube belongs there and should be implemented as soon as possible.