Scholastic
Scholastic: National Poetry Month
A bunch of great poetry resources and lessons! Each lesson lists grade appropriateness. Although this site was created with national poetry month in mind, most of the lessons can be used any time of year.
Annenberg Foundation
Annenberg Learner: Respond to Student Writing: The Watch Glass
Use an interactive rubric to evaluate areas of strengths and weaknesses in a student's poem comparing school to a watch glass. Then compare your responses to another teacher's.
Other
Kalliope Poetics: Online Poetry Workshop
This site tells what a limerick is and, gives a few instructions on how to write one. It also includes info on the traditions of the limerick.