When it comes to custom ROMs, we generally stick to covering CyanogenMod and – more recently – AOKP. Every once in a while, though, something really special, unique, or just downright awesome shows up in another ROM. In this case, it's PIE. A ROM that can make pie. No, wait, that's not right. It's a feature baked into the Paranoid Android ROM that completely revamps the navigation area.
All pastry jokes aside, PIE is a fully-customizable replacement for the stock on-screen navigation buttons found in more recent versions of Android. It stays hidden off-screen, only to be brought to life by a predefined gesture.