ITheora is a PHP script allowing you to broadcast ogg/theora/vorbis only videos (and audios) files. It's simple to install and use. It may suit the usual blogger or the expert webmaster.
Sajax is an open source tool to make programming websites using the Ajax framework — also known as XMLHTTPRequest or remote scripting — as easy as possible. Sajax makes it easy to call PHP, Perl or Python functions from your webpages via JavaScript without performing a browser refresh. The toolkit does 99% of the work for you so you have no excuse to not use it.
jMaki is an Ajax framework that provides a lightweight model for creating JavaScript centric Ajax-enabled web applications using Java, Ruby, PHP, and Phobos.