The Academy of American Poets has a lovely site, and as primary sponsors, devotes a bit of bandwidth to National Poetry Month.
The Poetry Society of America has a good collection of links to sites for poets, both dead and alive, and organizations supporting and promoting poetry.
The American Verse Project is assembling an electronic archive of volumes of American poetry published prior to 1920.
About.com on poetry provides just about everything and is a great place to start a poetry project.
Against National Poetry Month As Such by Charles Bernstein. A humorously serious perspective on National Poetry Month.
Celebrate Children's Poetry ... All Year Long! Children's writer Kristine George presents useful activities for teachers and librarians to engage children in poetry.