Here are some interesting sites worth checking out:
Poetry.org's NaPoWriMo page (Suggested Poetry Month activities; 30 Poets, 30 Days; Poem a Day; Spring Book List; National Poetry Map)
2012 April PAD Challenge, by Robert Lee Brewer of Writer's Digest
NaPoWriMo.net, allowing participating poets to list the sites where they will publish their NaPoWriMo poems; will also feature daily prompts
Scholastic.com's National Poetry Month page, with great ideas for children pre-K through grade 12
30 NaPoWriMo Writing Prompts, some of which are kind of fruity but might inspire someone. The same blogger offers 30 More NaPoWriMo Writing Prompts, which look promising.
If I find more, I might share them, as well.
One note: I will be posting my poems as "friends only" to make them (I hope) invisible from search engines. That way I won't have to remove them later if I want to submit them to magazines or contests. So if you're reading this blog and are not a mutual friend, but want to be able to read my NaPoWriMo poems, please send me a message!