Re: GNU screen
...or look at the Freshmeat project page (http://freshmeat.net/projects/screen/).
I suggest you take a look at GNU Screen (ftp://ftp.gnu.org/pub/gnu/screen/) which is a similar sort of tool except it works on any tty (xterm, xvt, aterm, Linux console, serial terminal, telnet session, etc.) not just X11. Its many features include cut/paste, split screen, connection sharing (multiple clients accessing same screen sessions, great for two xterms) and session disconnection/reconnection. It's a must-have for those intermittant serial or network connections.
An open, cross-platform journaling program.
A scientific plotting package.