One of the big changes building on the Web over the past years has been the availability of increasingly sophisticated applications - for free. Some web developers who at one time invented from scratch are now becoming expert integrators of open source applications. It's an exciting development because it means more of us can be creative and inventive. You'd be amazed by the number of really impressive websites are built using open source applications like WordPress, Joomla, or SilverStripe. Or the incredible knowledge-sharing possibilities of wiki-based intranets and extranets.
Open source software isn't quite the same thing as social networking sites or web-based APIs such as Google Maps. Facebook, Myspace or even Blogger offer users free access, but are supported by data mining and advertising to pay for the servers, development and technical support. Open source systems are hosted on your own servers (or the servers you pay for), and stand apart from other installations of the same system.
Conceptually, though, open source and social networking sites share a basic principle: pooling knowledge and sharing expertise create value. Many open source systems are designed by individuals and groups who believe in collaboration (and the possibility that their system will catch on and they can go to IPO). I am constantly amazed and impressed by the dedication of core developers and the more casual contributors who bring tools into the digital commons.
Top 10 Wiki Engines: