Not An Idea. A Question.
Ideas for Startups is an interesting article from Paul Graham (he of Painters and Hackers fame) debunking the common myth that you need a killer idea to build a startup.
He claims that a question is a much better starting point - it’s harder for a critic or detractor to attack, and lots of startups end up producing something quite different from their initial idea after it evolves through their trying to solve the initial problem. (Flickr is a prime example of this - it started life as an online game, and morphed into the photo-sharing site as they watched what the users were doing with it)
And then he goes on to explain why it’s useful to have more than one person in the startup (which I agree with, despite being in a single-person startup), and rounds things off with a discussion of getting acquired.