Calcium reactor, ORP reactor, Heater/Chiller, Multiple Timers, Wavemakers to name a few. You can set it to turn off your lights should the temp go too high, the list is pretty long of what a controller can do. Even though some are a bit pricey, when you think about it, they do a LOT for the money.
I have 5 timers alone on my tank, that is a quarter of what an AC Jr. w/the DC8 would cost.
This might help you out,
http://www.aquariumcontrollers.com/f...ntrollers.html