Check out the Telkonet thermostat. I’ve previously written about the Nest thermostat and the Honeywell Wi-Fi thermostat. Telkonet claims to take it another step further. Not only is their thermostat programmable, accessible from the Internet and “smart”, but it can calculate roof comfort by aggregating data like time-of-day, solar load, brightness, humidity and occupancy patterns. It’s Ecoinsight feature determines when a space is occupied or vacant and reverts to preset temperature limits. Check it out at their site here.
The Ecoinsight thermostat is more for commercial applications than the other two. While it has Internet connectivity, it may require special networking in order to access it. This is more efficient where you have multiple installations.
There’s an interesting blog post at Peregrine Energy Group here which has some good information about the various intelligent thermostat options including Telkonet’s version here.
I still haven’t made up my mind on which I like best. I purchased a Nest for my parents. (They haven’t installed it yet.) I’m looking into installing the Honeywell stat at our office. Contact me if you want more information as I “live” with these installations.