A very basic version of Cowsay in GO. But with Rainbow text.
$ git clone http://github.com/ennisstephen/rainbowcow.git
$ cd rainbowcow && go build
then
$ echo "Hello World" | rainbowcow
_____________
/ hello world \
\ /
-------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
Except it's rainbow. Use this as a learning or productivity aid.