Cato Unbound is one of my favorite discussion forums on the web. Initiated by the Cato Institute, an libertarian think thank, experts from all sides of political spectrum exchange their ideas about a certain political issue. Previous issues included interesting topics such as:
Can Marriage Survive?
Religion and Politics, Home and Abroad
Who Needs Government? Pirates, Collapsed States, and the Possibility of Anarchy
Rethinking Health Insurance?
When Does Inequality Matter?
The Living Constitution
They have started a new discussion under the motto "Is limited Government Possible?" which interests me very much.