Zooborns is possibly the cutest website ever. They pull all new stories from other publications regarding the birth of new animals at zoos around the world and post them up on their site.
Having a crappy day? Check out the baby sea horses at Monterey Bay Aquarium. They are so tiny they don't even wrap all the way around a blade of grass. Who could be sad after looking at a cutie like that.
Also great for children, who will appreciate seeing other creatures their own age. It's updated on a regular basis, be sure to check back frequently.