Oh, I don't know. Having a team that can solve any arbitrary difficult problem in three days could be quite useful in a startup. The (technical) execution of a startup idea can be cast as a series of arbitrarily difficult problems, after all.
My two long term pet peeves for which I would be most happy to help lobby to get them a hearing:
1) Faster than light travel 2) Create a robot that carries it's own power supply, communication device, and webcams that would allow me to traipse up and down any path in Rocky Mountain National Park in real time so that I can take a hike for 20 minutes when I need a break without the requisite plane travel and hotel bill
I suspect pg would be willing to pay for at least number 1 :-)
They better get cranking, because 72 hours is just not a lot of time to develop either of these things.
AFAIK YCombinator is for creating startups, not for letting outside people be a part of one.
You want to prove your will? Ask your neighbours, parents, friends, people you find in the street, ask them for what troubles them, what little things they have to do what would rather not. Find a way to solve it, charging money, low enough that they would rather pay, high enough that you cover costs.
Then you either have a nice startup of your own or at least you have some experience that you can share here. Repeat until success or bust.
This post is essentially asking PG to come up with an idea for them.