Rafael Gurkovsky, Life hacks (Productivity): Second Monitor
Now this might seem irrational, but a second monitor can actually make it easier for you to work. Employees notice that switching from one window to another actually makes it harder for them to concentrate on what they're doing. With a second monitor, however, it seems as though the whole process has just become way easier, no to mention easier on the eyes. Also, monitors today have become cheaper so this shouldn't dent your bank account too much.