I recently bought some Estimote beacons (a 3rd party iBeacon-like device) - largely because they seem like a cool and nerdy kind of thing. It has an Android SDK which will allow Android devices to interaction with devices. With a little big of effort, I managed to create Xamarin.Android binding and port the sample Android project provided by the Estimote SDK.
You can see an example of the app in these screenshots:
My Xamarin.Android port of the sample project is slightly different than the sample that Estimote provides. The obvious change is the use of a QuickAction menu that popups up when you select an Estimote. I found this to be a more intuitive interface than what came with the default Estimote example. The menu provides you with two options:
DistanceBeaconActivity tries to estimate how far away the selected Estimote is. Estimote refers to this as “ranging”. The outer blue circle is 6 metres, so the screenshot below was taken when my phone was about 3m away from the estimote.
NotifyDemoActivity activity shows how to fire off a notification when the user walks into a “region” that the mobile device has moved into the vicinity of some beacons.