Newspaper Editorials 
Write a letter to the editor regarding an editorial with which you disagree. 

Local Meetings
Attend a school board meeting or a town, or city council meeting. Speak up, and when you get home, write out your platform and submit it to your local paper's editorial desk.

Activist Groups
Go to a meeting at your school or in your neighborhood about a social, environmental, or other issue you care about. To get really fired up, go to a meeting representing the other opposing side!

Artistic Works
See a movie, read a book, listen to a CD, or eat out at a restaurant. Then, write a review about its merits and/or flaws. 

Online Debates and Resources:

New York Times Upfront
Discussions on controversial issues

Debate Central
Resources for policy debate

PBS Frontline Pro/Con
Gambling
Gun Control
Genetically Modified Foods
Minimum Sentences for Informants
The Death Penalty
Stem Cell Research