oldie but

http://badgods.com/limerickpoems.html
-> http://www.metafilter.com/63163/There-once-was-a-girl-named-Lenore

But this'n I couldn't resist:

Anarchy has been released
The good ones are worse than the least
The bird's hearing stinks
And then there's a sphinx
Congrats on your new baby beast!