the link above, Spyder Robotics, makes the HerpStat 2, which i have so pathetically simulated. Its like a thermostat and dimmer (rheostat) in one. It monitors the temp and adjust the amount of current going to the appliances so that their output doesn't surpass the desired temp. Unlike a simple on/off thermostat that just runs the appliance at full power until it reaches the desired temp, then just shuts off until the temp goes down a few degrees, then turns back on, and so forth (this is how your house's HVAC thermostat works)
Great thing about the H-2 is that it can monitor 2 different heaters set for 2 different temps at once.
Whats more, its only $175 - which isn't nothing, but its not crazy money either. If two or three times you want to go out to dinner, but make yourself a sandwich instead, its pretty much paid for.