WordPress FAQ is a cool plugin for creating your FAQ section . It has a lot of parameters to set, and it will allow you set your own theme from scratch. It has a user-friendly front-end and back-end interface, allowing you to set all parameters quickly and easily. FAQs have SEO-friendly URLs.
X File Explorer (Xfe) is a filemanager for X. It is based on the popular, but discontinued, X Win Commander. Xfe is desktop independent and is written with the C++ Fox Toolkit. It looks similar to Windows Commander or MS-Explorer, and is very fast and simple. It features file associations, the ability to mount/umount devices, a directory tree for quickly changing directories, the ability to change file attributes, automatic registry saving, the ability to view/create/extract compressed archives, and much more.
X-Plane is a flight simulator that reads in the geometric shape of any aircraft and then figures out how that aircraft will fly. It does this via an engineering process called "blade element theory", which involves breaking the aircraft down into many small elements and then finding the forces on each little element many times per second. These forces are then converted into accelerations, which are then integrated to velocities and positions. This gives X-Plane the most realistic flight model available for personal computers.
XChestival is an improved version of xchat_speak designed for Italian. It lets xchat and irssi "speak" through festival. It comes with a script for xchat and irssi and the Italian phonemes. The scripts have some useful features like channels and query filtering and string substitution.
XWiki is a WikiWiki clone written in Java that supports many popular features of other Wikis like the Wiki syntax, version control, attachments, security, and searching, but also many advanced features like templates, database and dynamic development using scripting languages (Velocity, Groovy, Ruby, Python, PHP, and more), an extension system and skinability, J2EE scalability, an XML/RPC remote API, statistics, RSS feeds, PDF exporting, WYSIWYG editing, an Office viewer and importer, and a lot more.