In a recent post I did on WebWorkerDaily, I provided three efficiency tips for using dual monitors. I recently switched to a dual monitor setup, and I'll never go back to using a single monitor. The efficiency benefits are tremendous. Not only can you treat the large amount of screen real estate that two monitors next to each other create as one long tapestry of desktop space, but you can also pick logical ways to organize multiple applications that you're running so that you can see a lot of information at once. If you do any type of writing or graphics work, it's essential.
Many of us live within browsers all day, and I've made the point several times that the lion's share of innovation is going on in the open source browsers, especially Firefox and Chrome. I use both of these browsers concurrently throughout the day on dual monitors, and here are some of the many benefits of doing so.