TWiki is a flexible, powerful, and easy to use enterprise wiki and collaboration platform. The structured wiki is typically used to run a project development space, a document management system, or a knowledge base, on an intranet or on the internet. Web content can be created collaboratively by using just a browser. Users without programming skills can create web applications. Developers can extend the functionality of TWiki with plugins. Administrators can tailor their TWiki installation with over 400 extensions available from TWiki.org....

Piwik is an open source (GPL license) web analytics software. It gives interesting reports on your website visitors, your popular pages, the search engines keywords they used, the language they speak… and so much more.

Piwik aims to be an open source alternative to Google Analytics....

Unfancy JavaScript,

KMyMoney is the Personal Finance Manager for KDE.
It operates similar to MS-Money and Quicken, supports different account types, categorisation of expenses, QIF import/export, multiple currencies and initial online banking support.

The Open Web SSO project provides core identity services to simplify the implementation of transparent single sign-on as a security component in a network infrastructure. It provides the foundation for integrating diverse web applications that might typically operate against a disparate set of identity repositories and are hosted on a variety of platforms such as web and application servers....

Portupgrade (aka pkgtools) is a tool set for working with FreeBSD ports and packages. It enhances abilities of the system tools and adds many new ones.

Tracker is a first class object database, extensible tag/metadata database, search tool and indexer.

It can trawl through your hard drive and index existing files and data stores

It has been designed from the ground up to be very lightweight (the tracker daemon consumes ~4MB of RAM in typical use) yet at the same time very fast too....

GKrellM is a single process stack of system monitors which supports applying themes to match its appearance to your window manager, Gtk, or any other theme.

Common things are easy, special things are possible

Xtext is a framework/tool for development of external textual DSLs. Just describe your very own DSL using Xtext's simple EBNF grammar language and the generator will create a parser, an AST-meta model (implemented in EMF) as well as a full-featured Eclipse Text Editor from that. ...

FreeSWITCH is a scalable open source cross-platform telephony platform designed to route and interconnect popular communication protocols using audio, video, text or any other form of media. It was created in 2006 to fill the void left by proprietary commercial solutions. FreeSWITCH also provides a stable telephony platform on which many telephony applications can be developed using a wide range of free tools....