AWK tricks - clearing the screen and scrollback buffer.

You can put this in your logout profile to fill up the screen buffer (clear just won't do on some systems with a multiple page console scroll-back buffer).

Filling the screen buffer with new lines:

awk -F 'BEGIN{ for (i = 1; i <= 3000; i++) printf "\n"; exit}'

See also:

http://www.openbsd.org/faq/faq7.html#ConsoleClear