ctrlxmms is a small Perl script designed to increase the useability of XMMS. With it, you can use most of the common GUI functions of XMMS from the CLI. You also have a few handy commands which are not available from the GUI. Together with lirc and a remote (eg. Anir Multimedia Magic), this is a wonderful tool.
CUPS is a wonderful printing system that uses the emerging IPP protocol. The only drawback is that there is quite no free driver available to print with. CUPS-drivers address this issue by providing a generic printer driver using GNU GhostScript. Not many printers are supported to date, but all is in place to support as many printers as GS can. If GS supports your printer, then CUPS-drivers will support it as well. Help and feedback are welcomed.
CURSEL is a freeware FMLI (Forms and Menu Language Interpreter) implementation for Linux and UNIX. CURSEL interprets Menu description files, which are simple text files, describing a character GUI (Menus, forms, text files) for character terminals (xterm, vt100, etc.). Pipes, shell escapes, backquoted expressions, and file redirection are supported, and when compiled with ncurses 5, CURSEL supports color.
CustomDNS is a modular DNS server written in Java. It's based on Brian Wellington's dnsjava pacakge, but it adds support for virtual hostnames, SQL databases, and dynamic client updates. You can use CustomDNS out-of-the-box as a clone of ml.org/dyndns.org, or you can use it to develop custom DNS applications.