I remember studying about Haiku in middle school, but it didn't make much of an impact on me. Now, as I have read haiku more recently, I think it could be useful in my classroom. There's a book called Tonight They All Dance published by Bolchazy-Carducci. Latin teacher Ginny Lindzey has written a review of it here. We write cinquains and diamontes, but it would be nice to have a completely different type of poem for variety.
While there are a number of "guidelines" for writing haiku (mostly having to do with the themes chosen, etc.), it seems the basic idea of a haiku is to have three lines of 5-7-5 syllables. The examples in the book are really neat in that, for the most part, the haiku fit the 5-7-5 pattern both in Latin and in English and are translated equally well in both.