I never want to bump into my ex-girlfriend while out in the city (talk about a buzz kill), so if I could get an alert telling me that she's at Shortstops down the street, I'll avoid that area completely. This is where the new, interesting app Cloak - Incognito Mode for Real Life from dev Brian Moore comes in.
Unlike SocialRadar, which kept you up-to-date on your friends' locations, Cloak is an "anti-social network" that basically alerts you when someone is nearby so you can avoid them. It relies on users avidly checking-in to places via either FourSquare or Instagram.
Your friends do not need Cloak in order for you to be alerted of their whereabouts. Say my ex takes an Instagram pic and adds her location, which happens to be near me, Cloak will send me an alert informing me how far she is.
The app itself is pretty minimal and simple to use. You don't need to create an account, just sign in with your FourSquare and/or Instagram account in order for it to gain information about your "friends".
You will also need to enable the location services for Cloak, otherwise it won't do shit. After all, it will need to know where you are to be able to show you how far away everyone else is.
When you do finally sign in, the main screen is a map with your location and the number of people that are located.
You can view the people that are mapped out and see how long ago it was that they were located.
Tap on the three-person symbol to bring up your friend list. From here you can tap to view friends by Distance or A to Z, and you can tap on an individual and Flag them.
Go into Settings to distinguish Alert Distance as well as if you want notifications from not only flagged people, but all people.
Cloak is not yet integrated with Facebook, which will definitely boost its functionality when it happens. As more and more social networking apps are integrated, it will become much more useful, especially since we will all be tracked in some shape or form in the future.
Also, it will depend on how often your friends check in or allow their location to be tracked. If not, then there's no use for this. I see this app being used much more in the coming years, but it definitely can help out right now in its infancy.