I just discovered that gnuplot has an xterm terminal output mode which uses xterm's tektronix emulator (since gnuplot 4.2.6). This is useful if you have logged into a remote machine and want to plot something, but you didn't have the foresight to use ssh -Y to bring along a connection to your X server. I used to use

gnuplot> set term dumb

but often the low resolution available with standard terminal characters left the resulting output almost unintelligible. With

gnuplot> set term xterm

your xterm will pop up a new window in tektronix mode, in which you get very nice monochrome graphics.

Besides the “forgot to tunnel X” use case outlined above, this output would also be useful if you wanted to avoid exposing yourself to X vulnerabilies while logging into an untrusted machine.

Obviously, you'll have to be running xterm for any of this to work ;).