MirrorBrain is an open source framework to run a content delivery network using mirror servers. It solves a challenge that many popular open source projects face - a flood of download requests, often magnitudes more than a single site could practically handle.
Universal Feed Parser is a Python module for downloading and parsing syndicated feeds. It can handle RSS 0.90, Netscape RSS 0.91, Userland RSS 0.91, RSS 0.92, RSS 0.93, RSS 0.94, RSS 1.0, RSS 2.0, Atom 0.3, Atom 1.0, and CDF feeds. It also parses several popular extension modules, including Dublin Core and Apple's iTunes extensions.