elbo.ws is an online feed aggregator that aggregates music blogs exclusively. It detects links to mp3 files and then extracts the id3 tags from the mp3 files.
elbo.ws uses this data to allow users to search through all the blogs and links to mp3 files are checked routinely to ensure they are still active. The site also compiles charts of how many times artists and tracks are linked to in order to gauge an idea of the band's popularity in the blogosphere.