The Haiku Foundation has done a lot for haiku and haiku poets since its inception. Right now, it's sponsoring a three-category haiku contest with cash prizes and no entry fees.
The HaikuNow! Contests consist of three different haiku contests: one for traditional haiku, one for contemporary haiku, and one for innovative haiku. Each person can enter one haiku in each category, and each of the three category winners will receive $100. Honorable mentions will get $25 each.
The deadline for these contests is March 31st, and all submitted poems must be unpublished. Guidelines for each of the different categories are linked to from the contest page.