Scalable Percolation Search in Power Law Networks is really interesting. I really ought to read about half of the citations, especially because they keep throwing around this phrase "bond percolation". (Their tendency to emphasize random phrases is a little annoying, though.)
Did you know you can search for ranges on numbers on Google? What's especially interesting about it is that you can do searches of huge ranges efficiently. On Monday I read the doc on how it works-- it's pretty awesome.