The x264 QuickTime Codec is a QuickTime Image Compression Component which uses the free, open source x264 H.264/AVC encoder. It can produce H.264 encoded video faster than the Apple-provided H.264, with more configurable options and better quality.
Elgg is an open source social platform
Elastic Utility Computing Architecture for Linking Your Programs To Useful Systems - is an open-source software infrastructure for implementing "cloud computing" on clusters- aka "open source ec2"
GoalBit is a peer to peer distribution system, capable of distributing high-bandwidth live-content to all network peers preserving its quality. This project follows a bittorrent-like approach where the stream is decomposed into several flows sent by different peers to each client. In order to meassure the peers perceived quality, it is used the recently proposed PSQA (Pseudo-Subjective Quality Assessment) technology.
gift/openft/gnutella frontend and daemon for macosx
Chickenfoot for Firefox: Rewrite the Web