One of my friends just bought one of these thermostats, and they look very cool. The Climatouch C3 is a touch-screen thermostat, that is supposed to work with any heating an cooling system. It looks like it has some interesting features that allow you to same money.
One cool thing that this does is allows you to connect a remote sensor, so you can see outside temperature. Unfortunately, it doesn't look like you can use can use it to monitor the indoor temperature of a different room. Ideally you would be able to configure it so that the air conditioner would come on if either the upstairs or downstairs gets warmer than a certain temperature.