Twin is a text-mode window environment. It turns a text terminal into a X11-style display with window manager, terminal windows, and can also serve as display for remote applications. Each terminal window provides the functions of a text-mode Linux console. Twin runs on X11, libggi, itself, the Linux console, and any termcap/ncurses-compatible tty. It supports multiple simultaneous displays, and can attach/detach each display on the fly.
Mrxvt (previously known as materm) is a multi-tab X terminal emulator based on rxvt/aterm. It supports multiple tabs, runtime dynamic tab title, pseudo-transparent backgrounds, user-supplied background images (JPEG, PNG, or XPM), background color tinting, text shadows, NeXT/rxvt/xterm/SGI style scrollbars, XIM, multiple languages (Chinese, Korean, and Japanese) and logging. It is lightweight and fast, and only depends on Xlib.
Viewglob is a filesystem visualization add-on for Bash and Zsh. It tracks the command line and environment of any number of interactive shells (local and remote). A graphical display follows the currently active terminal, listing the contents of directories relevant to its shell and highlighting file selections and potential name completions dynamically.
Qodem is a re-implementation of the Qmodem DOS shareware communications package, updated for more modern uses. Major features include Unicode support, scrollback buffer, capture file, screen dump, dialing directory, keyboard macros, script support, Xmodem, Ymodem, Zmodem, and Kermit. It can connect over serial port, telnet, ssh, rlogin, and command line, and supports multiple terminal emulations including ANSI.SYS, Avatar, VT100/102, VT220, and Linux.