Grow room automation comes in all forms.  The simplest form of automation are the timers almost all of us use for our lights.  Depending on the size of your setup, and the budget you have to work with the sky is the limit.  You can get low cost temperature controller that can turn fans, heaters or A/C on or off to keep optimal temps.  You can find the same for humidity and Co2 controllers.  Above that you can combine 2 or more of the environmental factors you would like to control. Like temp and Co2 for example.  Syncing up multiple devices so your ventilation fans won't waste precious Co2.  If you have the funds you can gain control of pretty much everything in your grow room.  

  

I believe automating your grow room in no was is a substitute for you having to be in there putting in work.  I hear all the time that people don't want to automate because they like to be hands on with their garden.  but lets face it.  I haven't met one person that sit there watching the temperature and turn on a fan.  Then I get an oh yeah when I bring up the fact their timer is automating when the lights come on and go off.  In all honesty about the only automation that I can think of that saves you time is having your reservoir changes done for you.  The time saved is minimal when it comes down to it, but that time saved gives you more time to actually take care of the plants.  

I remember when I got my first controller that had 2 knobs on it to set when the fan turned on, and when a dehumidifier kicked on.  It was awesome and I notice a huge difference the first harvest.  The plants where happier and it showed.  However I soon realized that with only 2 set points there was no way to have the control I wanted for both day and night.  Throw Co2 in the mix and it created a whole new world of issues.

From there I picked up a Growtronix system and have not looked back since.  I won't go into details here, but you can check out the Growtronix review for more info.  Having all the equipment in you garden communicating with each other is priceless.

It seems that every other day there is a new controller coming out on the market.  The larger players in the indoor gardening game have all seemed to come out with there own controllers. Along with new companies popping up.  A good amount of those companies pop up and then just disappear.  It is my goal to someday have a few identical tents set up and put some of the better systems out there head to head. here is a list of some of the controllers I have seen out there.