TaskPlace is a to-do app with a place location feature. It uses iBeacons to associate your tasks and todos with a place. The app sends you a notification about the todo if you come to such place.
For example, you create a task "Get the papers" and associate it with Home. Then, when you get home, you will receive a notification to take the drops.
Also you can create time reminders and repeats.
An iBeacon is an antenna that generates a bluetooth signal. The phone is constantly looking for such signals and, when in the range, tells that to TaskPlace app. The app shows you the notifications associated with the current place. iBeacons are sold separately, but the app works without them as a regular to-do list.
Low Energy Bluetooth technology is very energy-efficient. It has almost no effect on the charge of your phone and the beacon itself works with on battery that will last for up to one year.