The Open Web Analytics (OWA) framework provides a generic set of PHP and HTTP APIs that application developers can use to integrate web analytics into any application. The Framework also has built-in support for popular web applications such as WordPress and MediaWiki.
Multi-protocol Proteus is an Instant Messenger that uses the IM framework libpurple and is written using Mac OS X's API Cocoa. Proteus attempts to bridge the gap between functionality and beauty, using native the Mac interface with a powerful core to get your hard core instant messaging done.
Still demo, opensource software for web conferencing. BigBlueButton version 0.63 shipped with support for conversion of Microsoft Office documents, localization, API examples and more.