I have to laugh when I hear people say they could "build a better-looking Craigslist" in "a few months" or "a few weeks" or "a weekend" [or insert your own time

I have to laugh when I hear people say they could "build a better-looking Craigslist" in "a few months" or "a few weeks" or "a weekend" [or insert your own timeframe.] Craigslist isn't just some simple bulletin board software and forums that Craig put up on the Web one night -- it's the result of years of steady growth, good customer service, good word-of-mouth, and just good business. Sure, you could build a localized classified ads service that looks "more modern" -- meaning it uses gradients for no good reason other than everyone else is using them -- but that's no Craiglist. Now, if you have a site that somehow gets past some major problem or irritation that Craiglist users face, then maybe you've got a chance. But if you're just putting a new coat of paint on an old, well-executed idea, I'm not seeing the opportunity there.