I really like what the Teachers College Reading and Writing Project is doing around argumentative writing, particularly the work collecting both digital and print resources at different grade levels to help students research and take a stance on a high interest topic such as whether competitive sports in schools are beneficial or harmful.
Two of my favorites are videos that Mary Ehrenworth highlighted at the October Saturday Reunion giving two sides of
the issue of chocolate milk being served in schools, the first showing truckloads of sugar being dumped on a school bus as a vivid illustration of the way serving chocolate milk in schools is an unhealthy decision and the second featuring a smiling representative of the Midwest Dairy Council explaining all the benefits of drinking chocolate milk. (I just saw Forks Over Knives. Can you tell which side I'm on?)
Teachers are always asking for resources: for persuasive writing topics, it's important that they be recent. TC is constantly collecting and organizing these resources as well as quality samples of student work that
can be used as mentor texts. I recently showed this link to teachers in an after school class around close reading and they were really enthusiastic: one of them recommended the set in the 2012-13 collection on cyberbullying.
Some teachers are worried that students will come home telling parents that a teacher has taught them a controversial topic with a bias towards one side. These text sets allow students to weigh both sides of a topic and come to their own conclusion.