LOVE this post from Professor Reviews. (Can that stick?) Rather than put out an overly complicated chart like so much of the infoporn out there, Phil offers a decision-maker's view of "second-tier" review sites and exposes the thinking that goes into deciding which ones you should care about. It isn't comprehensive; it's smart.
In the blog comments, there's some discussion of the relative prominence of different review sites in different local markets, and how are we to account for all of Phil's decision factors plus all the geo-specific differences in review site usage, competition, and prominence?
It is second nature to most of us here, but I often advise clients to conduct two sample searches across one or more search engines to get a snapshot of the review sites that should matter to them: query "[business name] + [geo] + reviews" <business name="" plus="" geo="" "reviews"="">and "[business category] + [geo] + reviews"<business type="" plus="" geo="" "reviews"="">, e.g. "rays new york reviews" and "pizza new york reviews" (or similar).
That is, get a quick visual overview of how a given brand and its local competition present themselves in reviews/search. Look at the review sites that place (Yelp vs. Yahoo vs. YP), the review sites that pop (who's showing gold stars, etc.), and the relative position of individual listings in a given market, which is a good proxy for what sites folks there are using.
With these simple data points, you can usually triangulate on a few review sites that should matter to a given business beyond Google+ and Yelp.</business></business>
