I've added a new gadget in the sidebar just under my post list. It's simply called Some Useful Sites, and it's going to have links to children's sites I have found useful.
Right now there's only one in the list. It's for Writing-World.com's Writing for Children page, which has links to a number of articles about various kinds of children's writing -- definitely more than just how to write easy readers. Of course, there are quite a few about picture books (which can provide some useful info that's applicable to easy readers) and even YA novels. (I've never understood why YA stuff gets lumped in with children's stuff. If you have any experience at all with both ages, you know they don't think anything alike!)
I'd like to call your attention to one particular article on that page. It's called Hi/Lo Books: Writing for Reluctant Readers. The article is old -- August 2006 -- but the info is still useful. Hi/Lo books, in case you've never heard of them, are basically easy readers written for older age groups that have trouble reading. Carolyn says my books may have some potential as hi/lo readers as well as the young readers I have in mind when I write; the reading requirements are that similar. So if you're interested in writing easy readers, you might want to take a peek at that particular article.
Eventually that new gadget should have quite a few sites listed. It's going to take me a while to dig up all the ones I've used, however, so be patient with me. Some have to be "refound" while others have to be checked to make sure the urls are still active. I'll get them all added eventually, so keep checking back.