HP Labs' Blog Epidemic Analyzer is a social network analysis application that uses their iRank algorithm to try to determine origins of memes. About the project:

"What we're trying to do is let users track how information propagates through networks. Specifically we are looking at how web based memes (for lack of a better term) get passed on from one user to another in blog networks. For our purpose memes are basically URLs (although multiple unique URLs can be the same meme this demo does
Blog Epidemic Analyzer