Just scanned X devices on my network using Android Network Toolkit (#ANTI3) by @zImperium Get it now: http://zimperium.com/anti.html
As you can see from the pictures, Anti is intuitive and simple to play with, and can as easily be used by security professionals as newbies. The screenshots was taking while using the open wireless network on flight from Oslo to Trondheim (flying Norwegian).
The app was used only to illustrate an example, where the sniffing was aimed at a friends smartphone (with his consent).
The sniffing screenshot is a good example of how easily adversaries can capture unencrypted traffic in open wireless networks.