Is it possible to use dual monitors with World of Warcraft?

If you are running a reasonably recent version of windows, the answers is Yes. I run Warcraft in full screen windowed mode and have wowhead open in a browser on my second monitor, along with my vent client.

If you can run two monitors you can use wow in windowed mode and not need to 'alt-tab' or otherwise minimize the warcraft windows.

http://www.google.com/images?q=warcraft+windowed+mode

You can obviously do this without two monitors and have quick access to firefox (or itunes, etrade, etc). There is a performance hit with windowed mode, but it does have dynamic fps (frames per second) to degrade game play video quality to compensate.

Issue with this is that if you are using two video cards, some video cards introduce some issues when you drag windows between video cards or span windows between two different video cards. This isn't an issue with Windows7 any longer.

You also likely want to adjust the setting 'play sound in background' as when you wow window doesn't have focus it won't play sound. So when your surfing wowhead (or stackexchange) you won't notice chats, yourself being attacked, ready checks, etc otherwise.

The "Full screen (Windowed)" display mode (in the WoW display options) is just what you want. It runs the game in windowed mode, but stretches the window to fill the entire screen and hides the title bar/borders/etc. You can switch to another application (say, a web browser on another monitor) and WoW will remain visible.

In contrast, if the game is running in "true" full-screen, switching applications will cause the game to disappear since it is no longer the active window. This is how full-screen apps usually work.

You take a very minor performance hit (a few frames per second at most) running in this display mode instead of true full-screen, but it's not noticeable and completely worth it.