MMapDSP is a small tool for Linux that emulates a memory-mapped sound device on top of a sound device that does not support memory mapping. According to the OSS documentation, memory mapping of sound devices is an optional feature. Unfortunately, a number of programs, particularly games, rely on it anyway. This causes lots of grief, especially with some on-board sound cards. MMapDSP should work with Linux on i386-compatible systems with OSS sound drivers or ALSA OSS emulation.
ANDReA is a LAMP-based system for registration of network clients using DHCP. Splitting the network into "boot-net" for unregistered users and a "real-net" for registered users makes it possible to gather information about users in the network. Additionally it is possible to detect active services (FTP, WWW, a game server, etc.) and unregistered computers in the network. It is mainly used for LAN parties.
rxvt-unicode is a clone of the well known terminal emulator rxvt, modified to store text in Unicode and to use locale-correct input and output. It also supports mixing multiple fonts at the same time, including Xft fonts, real transparency, and an optional embedded Perl interpreter that allows you to extend your terminal easily.