Craigslist has no advertising on their site and doesn't charge for listings except for a few small sections of the site in major metropolitan areas (the funds from which they use for their business expenses). I think it speaks to the state of the bubble we're in that one of the "blue chip" internet companies has a business model of "be an ultra-speculative investment as long as possible." Of course Amazon too, but I'd say Craigslist is a more extreme example.