It would be interesting to compare your ranking to that obtained by simply sorting by the number of alumni with their own wikipedia articles.
Heh, this is pretty interesting -- with the caveat that this really only makes sense as a ranking for research institutions (which I think the author addresses quite nicely in his definition of 'contribution to world knowledge'.)
Related note: at what point do we expect to see things like Udacity and Coursera to appear in the USNWR college rankings?
I've actually computed a PageRank vector for all articles in Wikipedia. If you are interested, Coursera is about 0.0013% of Harvard which would put it very close to the bottom of the ranking.