As a Java Developer?… YES… i just started to work on 2 monitors and its amazing… it saves a lot of time.
Before 2 or 3 weeks i use to work on one monitor… i would frequently use Alt + Tab combinations on that Windows machine to switch between windows and now i dont have to use those keys that often. Say if you are developing a web application using Netbeans or Eclipse IDE, what you can do is Open the IDE in the main monitor and Open the web page(Browser) you are developing in the other monitor… Change the code in the IDE located on the main monitor… and then just refresh the webpage in the other monitor. Quick huh… saves 2 button presses.