Over 10 years ago, a guy told me that two was the only way to go. I was intrigued with the idea. I had a little extra cash so I got me two.
I couldn’t believe how much better life was with two. I was lots more productive. Luckily I have had the resources to have two or more more ever since.

One time one of my friends came to visit and saw how I was hooked up and made fun of me saying “You can get by just fine with one” and proceeded to give me advice and show me how he could use one really effectively.

It was funny a year later I went to visit him and he had two. He too realized how much better his life was with two.

Several years ago I started using three. Now I am up to 4.

Heres a picture of my hookup.

Doing most of my work on the web I have found it to be essential to have at least two. However anytime I can get a setup with more it just makes it easier to keep a bunch of things going a once. I also have learned to hook up multiple computers and use only one keyboard and mouse. Something I am also starting to find more and more essential.

Go out a get you a second monitor. I often tell people it’s a drug I can’t kick.

Good luck and enjoy your new found productivity and freedom.

Check out these resources.
Synergy the way to share a keyboard and mouse between computers
Screen recycler
And of course wikipedia if you want the history