I know it, you know it, I know you know it -- you want some cute and cuteoverload.com just isn't enough anymore. Check it out.
It's
cutethingsfallingasleep.org
I highly recommend "SLEEPY KITTEN 30", aka Sleepy Coco, a little more than 3 quarters of the way down the first page, as of this post.
Squee!
EDIT: Yawns are and sleepiness can be contagious. Something also contagious is laughter. For that (a more work-friendly thing to be infected with), visit
http://www.cutethingslaughing.com/Warning: this one is full of human babies, though.