The Linux Serial Sniffer allows you to sniff serial data up to 460Kbs via a Comtrol RocketPort or to 115Kbs using the standard ttyS0 and ttyS1 ports. Sniffed output can be captured to disk or displayed directly on screen. A user filter is included to assist specific customisation. The Linux Serial Sniffer can selectively operate in either a "ghost mode" where there is no data flow time impediments, or via a "capture and forward mode", where the user can flexibily intercept and extend the data stream to suit from either direction.
This is the old BSD tn3270 made to compile under Linux/GLIBC. It is not perfect and not being actively maintained. Also in the same directory is 3270v4.1 from CERN, made to compile under Linux/GLIBC, which looks nicer. If you are interested in these programs, you may also want to look at the Linux tn5250 project.
tn5250 is a 5250 terminal emulator, used for connecting to IBM's AS/400 (now known as eServer iSeries) midrange computers. tn5250 implements TN5250E, which means it is capable of device name selection, and printer sessions. The emulator supports color, 132 column mode, and most other features found in 5250 terminals and Client Access' 5250 emulator. While tn5250 is text-based application, a script is included to run it in an xterm properly. If you don't know what an AS/400 is, this program will probably not be of much use to you.
Gsh is a graphical shell. It integrates a terminal window, a normal shell, and various GUI components into a single package which allows easier and more powerful operations than you can have with a shell and terminal window seperately. Gsh is already fully functional, but there are many avenues of devlopment yet to be explored.
The xterm program is the standard terminal emulator for the X Window System. It provides DEC VT102/VT220 and Tektronix 4014 compatible terminals for programs that can't use the window system directly. If the underlying operating system supports terminal resizing capabilities (for example, the SIGWINCH signal in systems derived from 4.3bsd), xterm will use the facilities to notify programs running in the window whenever it is resized.