We have some simple rules:
* you can't start anything new;
* you have to celebrate something being done - usually with a round of applause;
* there are no prizes - only the satisfaction of being done.
While there is plenty of coding, we've had designers finish their portfolios, screenwriters finish pilots, an artist finish his display, and even saw a sewing project completed.
And to top it off, we charge a nominal $20 for the weekend - with 4 meals, a great deal - and sell out every time.
We're putting together a howto doc to franchise the idea.. just need to finish it. ;)