Today Demián Denker - my college partner - and I just finished a web server with a prefetching technique [1] based in th PageRank algorithm.
The web server is an implementation of Optimizing Web Servers Using Page Rank Prefetching for Clustered Accesses by Victor Y. Fronov.
In our implementation, through the web server console you can watch the stochastic matrix, the PageRank calculation, the pages in the cache, the candidate pages for the last request and so on.
Also you can configure the size of the stochastic matrix, the amount of pages to cache for each request, the cache max size and a few items more.
Of course this is not a real web server, it is just for educational purpouses. But if you want to take a look at it, just send me an email.
[1] The moving of html files from hard disk to cache in anticipation of future users' requests.