Pros and Cons
CQ Researcher Online http://library.cqpress.com/cqresearcher/
Britannica www.Britannica.com
Discovery News www.Discoverynews.com
Arguments, facts, and examples, both pro and con, of hundreds of topics
Debatepedia
"The Wikipedia of debates - an encyclopedia of pro and con arguments and quotes on critical issues" http://idebate.org/debatabase
Google Scholar http://scholar.google.com/
Internet Public Library http://www.ipl.org/
Pros and Cons of Controversial Issues
Presents both sides of current issues in a nonpartisan, unbiased format.
http://www.nytimes.com/roomfordebate
Room For Debate by the New York Times
Sweet Search http://www.sweetsearch.com/