Is the counter in _real_ realtime? I mean, updated every seconds?

Do you have backend layer or your device is directly consuming the Facebook API?

I'm asking because with an intermediary layer you could provide different types of counter. In a few seconds, I could be able to choose from different sources of data for the counter. Through a simple web interface hosted by you.

Uses would becomes unlimited. Twitter followers, Foursquare checkins today/this week,...

Even number of kilometers traveled with runtastic as an example,... At max 100€ people could buy one for their home. More like a moving/interactive object for decoration. This market is potentially bigger.

I didn't found the price too high for a prototype.

And +1 for the NFC tag!