And now for something a little bit different...
I'm just sitting down at the desk now, with a concept for the game I'd like to make.
It's a fairly standard collect-'em-all game, except that there's a very short time limit, making it impossible to collect everything in one go. And the game only lets you play it once.
How is it even possible, then? By collaborating: you need to enter the password left by the last person who played the game (along with any comments they might have left to help you on your way), and at the end of your game, you can leave your own password in the LD game page comments.
A bit avantguarde? Sure. A bit ambitious? Absolutely! But I think it's something that can only really work for a jam like Ludum Dare, so I'd like to give it a go.
P.S. Any other Dropout fans here? I just heard Sam Reich's voice in my head shouting "YOU ONLY HAVE ONE SHOT!".