iOS/Android: If you're worried about apps tracking your location, it's not enough to limit your location sharing. You need to limit camera-roll sharing too. If you've ever given an app access to your camera roll - to take photos, or store screenshots, or any given reason - you've also let it see where all those photos were taken. Felix Krause, an iOS developer and security writer, built an app to demonstrate this back door.

The recent publication of a leaked video demonstrating American security firm Raytheon's social media mining tool RIOT (Rapid Information Overlay Technology) has rightly incensed individuals and online privacy groups. In a nutshell, RIOT -- already shared with US government and industry as part of a joint research and development effort in 2010 -- uses social media traces to profile people's activities, map their contacts, and predict their future activities. Yet the most surprising thing isn't how RIOT works, but that the information it mines is what we've each already shared publicly.

The EXIF data stored with photographs can be useful if you want to replicate the same settings on your camera, but it can also reveal information you'd rather keep private. If you want to remove all EXIF data from photos before uploading them, ExifPeeler is a bare-bones web site that will get the job done.

Windows only: Setting (and re-setting, and re-setting) your camera's clock can be a pain, but wildly incorrect photo timestamps even more so. Here's a free program that can keep your shots in sync.