I usually have 1-2 windows of documentation on one screen and 2-4 terminals open on another.[0]

This allows me to prototype, compile, test, build, look up info with minimal window switching. The biggest advantage is never having to hunt for the correct window--everything is one keyboard shortcut away.

[0]: http://i.imgur.com/xctkdtq.png

The empty black box is due to my right monitor being in a vertical position.