Never mind apps that tell the world where you and your friends are. How about one that tells you where people are you want to avoid? That's the selling point of Cloak.It's probably a good one too if you happen to bump into the same annoying person (or persons) on a regular basis. Saying that, there are obvious flaws with it.The main one is how it works in version one. You see, Cloak basically scrapes Instagram and Foursquare to let you know where all your friends and non-friends happen to be all the time. That's great if these people are avid users of both of those apps. Not great if they aren't. They'll be cloaked from Cloak.But as we said, this is version one. The people behind Cloak have pointed out that more social networks will be added soon, which should create a better picture of where people are and when. However, they also point out that Twitter is unlikely to be included as there is little location data available from it. Sadly for Cloak, most users turn it off.Even allowing for that, it's an app with potential and likely to be fun in the short term. Oh yes, it's free too, which is always a bonus.