If you write, Adventures in Children's Publishing is a great site to follow.
Don't write children's books? It doesn't matter.
The site features good writing tips — they apply universally to a variety of genres.
I found it long before I acted on my desire to write a picture book.
The tag under the blog's banner says: "Children's writers in search of readers ... and the information, market info, insider tidbits, and writing advice they find en route..."
The site has tabs on its contributors, quotes on writing, great openings, beautiful writing and contests & workshops.
I really enjoy the "Helpful Articles" column on the homepage. You can quickly find worksheets, writing tips and query information. One of my favorites is a Pre-Submission Checklist. This checklist is a great editing tool — even if you aren't ready to submit your work yet.