I am about to embark on an exquisite journey. I have applied for an event, where in span of 48 straight hours, strangers meet, throw around some great ideas, decide on teams, and make a working prototype of IT project. All within 48 hours.

I anticipate, that this will be very skill and ability intensive experience, and I want to be prepared. Since i will need to develop my part of the code quickly, I have a following question:

What would be the most needed skills for these 48 hours?

I do know, that things like proper documentation, version control and such are pretty important for a full fledged application/program/web development, but for this span of frantic coding?

Background: I am a web developer, so answers applicable to web development would be more appreciated than others.