Protector

Like to show off your Android phone to friends but worry about them reading emails they shouldn't or installing apps on you, then Protector is what you're looking for.

There is a free version and a paid version for $0.99. From what I've seen the only difference is the free version is limited to protecting only 10 apps.

The app is still in a beta stage but it's working pretty smoothly for me so far, I've only found one bug in it but otherwise I've been pretty impressed.

The free version is supposed to allow 10 apps to be protected, but for some reason my phone only lets me pick 7, I emailed the developer about it but haven't heard back yet. In messing around with the settings I found a simple work around for now. If you go to the settings screen (1st screen cap) and turn off the protect system apps setting, then go back to the apps screen and pick the apps you want, then turn back on the protect system apps it will let you pick more then the 7.

Right now it's a single pin code to unlock all the protected apps, the developer plans to add individual pins for each app in a future release.