-----------------------------------------------------------------

cowsay

example: cowsay "hello"

other cmds:
cowsay -l
cowsay -f character "text"
xcowsay "text"

example: cowsay -f duck "hello i am duck"

info:
shows a cow saying what you typed

----------------------------------

sl

example: sl

info:
shows a text steam locomotive driving across the screen

----------------------------------

yes

example: yes "hello"

info:
loops the text you typed until Ctrl+X is pressed

----------------------------------

rev

example: rev "hello"

info:
reverses the text you typed

----------------------------------

toilet

example: toilet "hello"

other cmds:
toilet -f mono12 -F metal Linux "linux"

info:
shows a fancy version of the text you typed

----------------------------------

cmatrix

example: cmatrix

----------------------------------

pi

example: pi "5"

----------------------------------

x11-apps

commands:

xeyes

xclock

xcalc

se all x11-apps here

or here on the official website

-----------------------------------------------------------------