When you have more than one computer and you're traveling, it helps to be able to access all your machines remotely.
I have several computers at home, and it helps to be able to control them all from a central computer. Running around from machine to machine can be a big pain. Using a remote control software is essential to being able to efficiently manage your machines. I have used several GUI controllers before: Microsoft's own Remote Desktop, Remote Administrator, VNC, Apple Remote Desktop, and of course when I'm going into my Linux boxes, I just SSH in--I'm not using any GUI on my Linux machines.
On the road, remote control is a real necessity. However, things can become problematic for those who have dynamic IP addresses. Once your ISP changes your IP, you'll have no access to your computer from a remote location. That said, there are several ways around this. You can use a dynamic IP client-service solution that allows your remote computer to automatically inform a live server of a new IP change.
For example: homepc.yourdomain.com can always point to the right IP address if you have a client installed on homepc. There are several services that offer this, DynDNS is a service I've used before.
More recently, I've been using LogMeIn (opens in new tab) instead. It solves the same problem that DynDNS solves, but you don't get your own sub/domain. It's really easy to use and you won't have to worry about dynamic IP services.
The question of the day is: What remote control software do you use?