Much has been written about new airport security scanners that can see private body parts.
The data is currently being discarded, one would presume, but it could have significant, and potentially beneficial, impact on all sorts of initiaves, in both anonymized and non-anonimized forms.
For instance,
while not necessarily alerting anyone on the spot, a note might be sent to you by mail that you should really see a doctor about something that came up on the scan -- remember the most times the scan is done while your passport or other identification is handy and your passage is likely logged already. (I'm aware that today such technologies use different wave frequencies from medical devices, but this is hardly a showstopper).
Or, on a lighter node, the goverment can use statistical data about whether its really winning that war against obesity, or an airplane manufacturer and airline can adjust their plane design based on the actual statistical distribution of their passengers.