I usually carry my laptop to work and manage to do most of my work on that. But I still have a desktop machine which stores a lot of the data as well the two other work email addresses I have to manage (in addition to my own.)
Having to move my laptop out of the way and work on the desktop every now and then was getting to be a bit of a pain, so the first thing I did was install TightVNC on the desktop so that I can remotely access it from my laptop.
Once I did that, I realised that the LCD screen that came with my desktop would then be redundant. And then the light dawned. I could hook it up to my laptop as a secondary screen and extend my desktop onto it! Woo hoo!
Fifteen minutes later and a lot of digging around under the desk for cables and such, I now have a very nice dual screen and dual computer set up.