cowsay is a little utility that as you can guess draws a cow on the screen and can display text with it
< hello > ------- \ ^__^ \ (oo)\_______ (__)\ )\/\ ||----w | || ||
However there are lots of nice options
cowsay -f tux hello
draws a pic of tux
< hello > ------- \ \ .--. |o_o | |:_/ | // \ \ (| | ) /'\_ _/`\ \___)=(___/
If you use the -l option you get a list of all the different ascii art files it can load in
Cow files in /usr/share/cowsay/cows: apt beavis.zen bong bud-frogs bunny calvin cheese cock cower daemon default dragon dragon-and-cow duck elephant elephant-in-snake eyes flaming-sheep ghostbusters gnu head-in hellokitty kiss kitty koala kosh luke-koala mech-and-cow meow milk moofasa moose mutilated pony pony-smaller ren sheep skeleton snowman sodomized-sheep stegosaurus stimpy suse three-eyes turkey turtle tux unipony unipony-smaller vader vader-koala www
so there are lots of options for characters.
You can also combine this with fortune which is another little program that comes up with random quotes from a large database of options
psutton@e-machines:~$ fortune | cowsay ______________________________________ / Tell the truth or trump--but get the \ | trick. | | | | -- Mark Twain, "Pudd'nhead Wilson's | \ Calendar" / -------------------------------------- \ ^__^ \ (oo)\_______ (__)\ )\/\ ||----w | || ||
If you put what you want at the end of .bashrc then when you start a console it will display the result and you can use it as a greeter for people logging in.
As always more info can be found in the man page