Android: There are handy apps that let you disable your Android password when connected to Wi-Fi networks, but this app takes that functionality further. Bluetooth and Wifi Unlocker removes the need to type in a passcode owhenever you're connected to a Wi-Fi network or a Bluetooth device.
Adding Bluetooth lets you keep your phone accessible when you're streaming music at home, to headphones, when you have your Fitbit attached, or when you're in your Bluetooth-enabled car (only while you're stationary, we hope). The passcode goes back on the moment your phone is out of range of your chosen device, so would-be snoops are out of luck if you're not near your phone.
Bluetooth and Wifi Unlocker is available as a free app, with tough limits on the number of Wi-Fi networks and Bluetooth devices and preferences. The $3 paid version removes those barriers.
Bluetooth and Wifi Unlocker [Google Play]