Tech Droid

Here's a simple and easy implementation for adding PIN lock support for your Android apps. The library can be themed with your app theme colors. It has smooth animations and vibrate cues when something's wrong.
To use this, you just have to write about 10 lines of code, including layouts and everything. It's so simple....

I found a few non-documented sensors on Lollipop (Android 5.0) on a Nexus 5.
Tried looking for them, but could't find any documentation on them on. Looks like they are mostly software sensors.
Here's the list that I have found. I have written a simple app that displays all the sensors and shows there values. Not to mention that, only for the ones that are documented. For the ones not documented, you can only see it's details....

Recently, Google released a new version of the Support Library, which has an interesting component. It's called SwipeRefreshLayout. With that, it's become a child's play to implement a quick Swipe-to-Refresh control for your apps.
A few things first
Available only with android-support-v13. Which means that only apps target SDK level 13 and above can use this....

Android KitKat has added a few more hardware sensors to it's API list. Step Sensors are one of them, which looks very promising. Although, not a lot of phones yet have these Step Sensors, in the future, this would gradually become a standard I think...