Limericks are wonderful. Because they're so easy and ubiquitous, a good limerick is actually high art.
We had some really wonderful sections on light verse in a few of my courses at the program. In particular, for our "80 works" course (a generative, fast-forward through the forms class) we were assigned several different forms of light verse, and the output was all regarded as seriously as for the other projects. Now, that's a grad workshop, not AP Lit in high school, which is where the stick first gets firmly planted, but I'm happy to report that quite a few academics, at least on the creative side, are taking light verse seriously enough to keep thinking about it after they stop laughing. I think the Clerihew was my favorite of the light verse forms, personally. Here's a fun one: There's no disputin' that Grigori Rasputin had more will to power than Schopenhauer. (by Dean W. Zimmerman)