We just had a 24 hour marathon at work, since we realized we were moving waayy to slow for a startup.
It was 3 of us - 8pm Fri night to 8pm Saturday night. I realized immediately that for the whole thing to work, some structure was required.
So this is what I tried.
1. We sat in such a way that all of us could see each other's laptops.. ie noone could goof off.
2. We sat outside in the open actually - no AC, but good powerpoints and internet.. sometimes it was sweaty.. but once we got into the groove, we couldnt bother about the weather. In such time, I guess it is helpful if there is a natural breeze around and it is not too cold.
3. The prohibited list - this was critical. We made a list of things that were banned. They included email, chat, facebook, games, blogs. These were banned even during breaks. And if anyone was caught violating the ban, a starbucks treat was due (noone violated :) ).
4. 1 hour work, 10 mins sharing. This was great at creating momentum.. after a while, we got so absorbed though that we forgot about the breaks :)
5. Blog - we had a little company blog where we decded post stuff through the night.. it provided some humour and relief.. I hit upon this only half way through.
6. We shifted places now and then (For dinner etc) to allow some stretching - it gets really tiring if one sits at the comp non stop for long periods.
7. Once we were done, we take 3 days fully off.
All in all, it was a hugely successful session! I am so full of energy 2 hours AFTER we finished the marathon. Would definitely recommend it if you feel things are moving slow in your startup/group/project. But, remember - the structure and environment are key!