There is an app called PDroid (but if you’re serious about security, you probably know that already) that lets you blacklist and whitelist apps using specific permissions. If you don’t want an app using a specific permission, block it. It’s quite a nice app to keep around, especially when you want to cut apps off from internet access. However, an XDA dev named CollegeDev made an addon for this app that enhances the functionality a little.
It does the same thing, except instead of permissions and personal information, it only deals with the camera and microphone. You can block any app from spying on you in such a fashion. Usually, we don’t think about apps accessing our microphones, but after Eagle Eye, this might be a good app to use. Stay on your toes….