A number of times I've looked for the kind of site you're thinking of making, roverroad, never with good results. I think it's a good idea. Info divided by categories, with user reviews, ratings, and info on popularity, service type, membership, etc. for each site could make it rather useful.
Say for example I wanted help removing some spyware...info about the top sites that ordinarily will actually get back to you with quick accurate info about it would be cool.
IMO, this is true though:
Craven wrote:Yeah, but unless it got lots of traffic nobody would pay attention IMO.
As for monetization, again I agree with Craven about getting sites to pay to be listed as experts in some field. But that doesn't need to compromise any accuracy of your site's info though...you can just do it like tucows does, listing "Pay per use", "Free", "Free with registration", "Contact for quote", etc. along with the listings.