I'd love for someone to write about howto meet people who you'd want to join up with you as a cofounder. I know I wouldn't be able to do any of my high in the sky plans by myself but I don't know many people who'd be up to taking the plundge.
Alternatively, you can identify the same set of people without actually running the ultra by looking for people who descend stairs backwards.
It was not advice - but an observation offered as a data-point. You can indeed meet people that run ultra-marathons without running one by going to meetups, fb group events, etc.
That's not exactly my field of interest but I'd sign up for something like that when I get out of college and need to finally get to building things.
Do the research before building anything, otherwise you could be wasting your energy on something people don't want.
An internet "dating site" for startup co-founders to meet on (you could have the whole shebang - ratings, chat, profiles).
Maybe something like LinkedIn meets Match.com, with a sprinkle of YC thrown in?
(note: I have no affiliation with them)