Here's a great post from Kelly Mortimer with a lot of helpful writing information. You can read the entire post here.
And if you want to find topics to write about, here is a list of 7 ways to track trends. Thanks to Writer's Digest. Check it out here.
Here's another useful link to read: Face-to-Face with an Agent, from Writer's Digest. Read it here.
Here's one more great post, which gives a list of agents accepting queries from children's literature writers, which was current as of March of '08. Check it out here