Page Rank is not a particularly impressive algorithm. The technical leap that Google made was the idea of having outgoing links be a proxy for authority, and it was an innovative and useful observation. Page Rank is about the second-simplest implementation of that concept (the first-simplest would not have the dampening factor). It's just a glorified eigenvector problem. Page Rank is not impressive for being a significant technical breakthrough. In fact, I think Page Rank is more impressive for not being a technical breakthrough. Google came up with a single good idea, and even a very very simple application of that idea had significant practical benefit.