AgentQuery – Provides information about numerous literary agents.
Behind the Name – This easy-to-use database of first names and their meanings is great for naming characters.
James River Writers – This is a great group, especially if you live around Richmond, VA. Even if you’re not local, it’s worth checking out for the annual conference alone.
Manuscript Wish List – Here, oodles of literary agents and editors post descriptions of what kinds of stories they’re looking for.
Society of Children’s Book Writers and Illustrators – A fun and useful organization to belong to, with critique groups, contests, and more.