Popcasts is an aggregator of ‘most popular podcasts’ (e.g. top 10 podcast). It lets you see at a glance, on just one page, what is popular in dozens of different podcast directories, without you having to constantly check the individual directories for the latest ranking results. It scans and synchronises with pre-registered podcast directories or ranking sites every hour and generates RSS feeds for each top 10 podcast. The sites registered to Popcasts include: Apple iTunes Podcasting, Odeo, Podnova, podfeed, iPodderX, PodcastPickle, Podcasting NEWS and Podcast Alley. Link.