Have been running and controlling our oil burner and pellet stove for 18 months now using 2 of these:
http://www.controlbyweb.com/x300/
These are industrial quality and work well.
They send their current, daily, I.P. address to dyndns.com.
I access a link at dyndns.com (for free) to monitor and control things.
If I loose the internet link, they continue like a regular thermostat.
I travel a lot and am able to monitor and control home from an iPhone.