uhat is a tool that listens to joystick events and converts hat switch axis events into the joystick button events X-Plane needs. Some joysticks have hat switches that are represented to the OS as two axes, even though mechanically they're just four 0/1 switches. These hat switches are often used for looking around through the cockpit in X-Plane.
ui is a user information utility that can display user information, list users from a given UID (or UID 500 by default), add a user to a group, rename a user along with his home directory and update his home directory files to reflect that change, list expired or locked users, change the shell for a user, and list users in an existing group.
uidentd (mu-identd) is a fast and secure identd/auth server. It runs on Linux and any other OS that provides the virtual files, /proc/net/tcp and /proc/net/tcp6. It supports IPv6 natively. It is launched from a superserver such as xinetd or tcpserver and is supposedly resistant to buffer overflows since it is written in Perl. It supports configurable connection timeouts and multi-query as defined by RFC 1413.
ulatencyd is a scriptable daemon which constantly optimizes the Linux kernel for best user experience. The default configuration tries reduce the latency for a typical desktop system and protects the system from malicious processes and groups. With a different configuration, all other types of systems can be adjusted as well.
Uldramar is a fantasy RPG and adventure game. You can cast spells like the mushroom morph spell and pick up objects for later use. The story is about a plane called Uldramar where there is a quest or two waiting for you. The game was influenced by the Ultima series and the Legend of Zelda.
Ulim is a Linux kernel module which enforces resource limits on every process in the system. There are already solutions like pam_limit, but there are some places where the user can execute his programs, but PAM is not used (for example .forward or .procmailrc files, or CGI scripts). Ulim works in the kernel and sets the limits whenever a process changes its real UID, so every process run by a user will have the correct limits.
ulock locks the entire virtual console system, completely disabling all console access. It gives up these locks when either the password of the user who started ulock or the root password is typed. It is able to invoke any program (i.e. a screen saver), which will be terminated on any keystroke. The idea of the program was taken from Michael K. Johnson's vlock.
ulogipac is a powerful IP traffic accounting tool for Linux routers and hosts. Users can use the power of iptables rules to specify which traffic to be accounted and which not to be accounted. The size of IP packets sent through iptables ULOG is counted and buffered. After a configurable time period the daemon submits the traffic information to database servers. Traffic information can be sent to more than one server to provide redundancy.