Check out the irreverently titled blog post, "10 Steps To a Hugely Successful Web 2.0 Company," by Charlie (no last name, apparently, ala Cher), an analyst at Union Square Ventures, where Fred Wilson of A VC blog rules the roost.
Snarkiness aside, I think the focal points of the piece are dead on. Take small bites in terms of the initial problems your product solves. Play the Tipping Point angle of mavens, connectors and salespeople in terms of engaging the market. Ship the idea quickly, then fix and iterate in rapid succession. Bake your offering as far and wide as practically possible out on the web (versus behind a walled garden). Be frugal in terms of burn, operate with humility and addict your users.
Good and crisp read, putting aside the many "anti buzzword" commenters who can't seem to separate the Web 2.0 cover from the book (not Charlie's fault).