It looks like there are several different users who want to build this (or something similar).
I definitely think collaboration would work best - if the site is going to be used by the community it needs all of our support. It can't be a one man show.
Personally, I envision a site with several different tools: idea feedback, find cofounders, find shared office space, demo new apps, a how-to resource archive, wiki, etc.
I think one News.YC reader has already built a site that can be used to find cofounders. Jamie, Sumon and Timmmah built a site to demo apps (demomyapp.com). Justin is building a basic idea feedback site. John Leung is trying to organize a shared office/startup hub website. I'm building a resource archive.
What if we all collaborated on one site that did it all?
Some of the features could have different URLs (for example, demomyapp.com wouldn't have to move) - but it'd be cool to run we all off the same server w/ the same theme/layout and same user authentication process.
Kind of like google accounts w/ google/gmail/google analytics/etc.
Funny, because I just registered a domain for something like that, ideasbin.com, one day before this thread started. It was a direct inspiration by YC, too: since everybody keeps going on about ideas being worthless, why not "throw away" your idea? It could also be a place to mourn your ideas that you'll never make come true.
My plan was to start simple, though (perhaps reddit style ideas submission, a wiki page for the idea, 'social net' in that people can collect their favorite ideas). Seeing the ideas taking form here, I guess ideasbin would not be too successful (should have picked a more serious domain name).
But anyway, in general I am interested to work on this, although actual time available might be limited. Email in my profile.
I may have some free time in a few months if anyone wants to team up and build it :P