National Haiku Writing Month (NaHaiWriMo) http://sites.google.com/site/nahaiwrimo/home/participation
Also see the exercise over at Andrew Shattuck McBride's section of Writer's Digest Community. During the month of February, where participants will post one haiku each day. Check it out on line at this link:
See also NaHaiWriMo's Facebook page at https://www.facebook.com/pages/NaHaiWriMo/108107262587697. You can find prompts for writing them each day at http://sites.google.com/site/nahaiwrimo/home/daily-prompts .