A whole range of apps:
I remember one which used the wonder of satellites and smartphone mapping to tell the profoundly stupid when they really shouldn't be standing somewhere - like on a high exposed ledge taking a selfie. Or lying on a railway track for a fun pic etc etc.
And a woman who it was clear to me had a pretty dysfunctional relationship with her partner, to the extent that they could hardly talk, once enthused to me about a wonderful "noise cancelling" app that allowed you to hear your partner if you were in a too noisy bar. Leaving aside the point that she never did anything as intimate as going to a noisy bar with him, I couldn't help pointing out that if you actually WANTED to speak to your partner you could jointly decide to leave.
