App that detects youve entered your house.

[SUroot]

As mentioned, I can set WiFi zones. Think it uses GPS coordinates from cell phone tower to recognize locations. As mentioned, it turns on when it is within the area. After one leaves the area, it will turn off WiFi after failing to connect. One can also set it to turn on at specific time intervals with peak/ non peak and night options. E.g. Peak - hourly, non peak - 2 hourly, night - go offline into aeroplane mode for example. From my experience, it helps save battery life.

I can't see how beaming information to and from space to work out when to turn WiFi on can save battery more than checking the time. I'd be skeptical that it actually did that

 

[yaronm]

PhoneWeaver has a 12 days trial period and then you have to buy it. It's the most expensive at 3.99. Both AutomateIt and Llama are $1.50 and you get a full ad version. If all three do the same things, AutomateIt or Llama would do the job.

AutomateIt has a nicer UI than Llama but when I try to set up cell towers profiles, it doesn't seem to be picking up any cell towers?

You can take a look at the following link to properly configure your Cell Id Trigger:
Android Muzikant: AutomateIt - Cell Id Trigger Guide

As for not picking up any cell towers, it depends on your reception. What I'd usually recommend is setting up a trigger that uses cell id and after a while, try and use the "Add cell (from recent)" option as described on the above link.
This will allow you to add all the cells that were connected to your device.

Alternatively, You can use the Location trigger as described on the following link:
Android Muzikant: AutomateIt Location Trigger - Tips and Tricks