This is a crazy cool interactive visualization of the relative influence and importance of philosophers. This guy simonraper (that's his handle anyway) did a data pull from Wikipedia determining what philosophers are identified as having influenced other philosophers and used a graphing platform to visually map it.
So the usual caveats about the data and methodology apply, but it's an interesting exercise to see how Wikipedia, as a reflection of collective knowledge, represents the relative influence of philosophers. The Times article notes, this isn't necessarily a representation of how important the thinkers were in history of ideas - it's a reflection of how the current Zeitgeist sees their importance. But if there is any merit in the 'scholarship' behind Wikipedia this shouldn't be that much of a bias. Acknowledging the influence of one thinker on another, from the outside, would itself only really be subject to the sin of omission rather than overt misrepresentation. You can't really get away with saying that Spinoza influenced Aristotle.
The Times author asks whether the same exercise for the Stanford Encyclopedia of Philosophy (or the Internet Encyclopedia of Philosophy for that matter) would turn out similarly. I think it would. If you read the author of the graph's methodology, he counted all relationships as equal. Nietzsche and Hegel are big because they influenced a lot of people (according to Wikipedia), not because they influenced some people a lot. This graph is a representation of how often thinkers are cited by the authors of Wikipedia as being influencers of others. I suspect the 'scholarly' resources would agree for the most part with these results.
This is circumstantially borne out by the fact that if you look at the large image of the graph, characters such as Eric Voegelin and Joseph de Maistre are influential enough to see not only see their names, but both are bigger than Maimonides and Nicholas of Cusa. If Wikipedia exhibited a non-scholarly bias towards figures perceived as influential today, no way would those guys be so big on the list. By which I mean only Philosophy geeks would be referencing them.
That said, there really aren't all that many big players in the grand scheme of things and any exercise like this should feature the same rogue's gallery: Plato, Aristotle, Descartes, Locke, Hume, Mill, Hegel, Nietzsche, Kierkegaard, Marx. With the exception of Descartes (a notable exception called out by the Times), this does. Now the real question is: who the hell is Murray Rothbard?