I often say that I don't know how anyone taught before the internet.
In fact, I usually take stock of what I need to teach, and then I start Googling. But, there are a few tried-and-true sites that I keep coming back to:
Are you guys familiar with Mo Willems? He is my favorite children's book author, and he is totally a rock star in my eyes. (Last year, I met him, and he signed my shirt!)
This site has tons of fun resources to go along with his books, including my personal fave, The Pigeon Finds a Hot Dog.
Picture Book features tons of illustrations from popular children's books. (I consider them fancy clip art).
This site is worth it for all of the fun coloring pages alone, but it also has craft projects and lesson plans.
If you could marry a website, I would marry Google.