There's a reason he has to emphasize legal, and that's because the obvious cash crop isn't. The market of capitalism has decided, and has found the best use of the land possible.
> Suppose you want to find a turnkey web site management company...
A listing site of vetted companies providing X service, unbribe-able by ad-dollars, would have to be subscription-only to be sustainable. Unfortunately charging for online content doesn't have the best history. Facebook and LinkedIn are positioning themselves to find said company 'close' to you that people can recommend.
> Think of it as Match.com for startups.
This one has gone around a couple of times here before, and ranges from an actual web app, to that google spreadsheet that comes up every once in a while. So, the need's definitely there. Arguably, meetup.com meets that need rather successfully.