Does a second monitor improve productivity?

I usually work with two monitors and a netbook.

Main monitor has my editor open for programming. Second monitor has a web browser (for references and such), terminal, PDF reader (for references and such) and music player. The netbook is used differently depending on what I'm doing, but I generally have a browser, a temrinal (usually more than one) and text editor open.

At the moment, my desktop is running windows and my netbook linux, so I often commit code to git, check it out on the netbook and do tasks that are easier on linux on the laptop (eg, anything where any sort of scripting would help). I use the desktop mainly for code editing and reading reference material because of the bigger monitors.

If I'm on IRC, its on the netbook. Chat is often open on both and I'll use whichever is most convenient at the time to reply to messages. I don't use social networks enough to say I predominantly use a second monitor for them. Youtube I use on all monitors equally (and not while working). Over all, social web is a very very small perentage of my second monitor usage.

Just ask Al Gore

Here he is preserving the earth's precious resources :

http://www.time.com/time/photogallery/0,29307,1622338_136300...