A cool feature coming to Android L which is currently available to developers are the notifications. These notifications will show at the top of your device and will notify you if you get an email, text message etc. you will also be able to interact with them.
If you just can’t wait till Android L becomes available or your device isn’t getting the Android L update you might want to install Heads Up! a simple app that doesn’t require you to root your device (or the Xposed Module) that will allow you to show Android L like notifications on any android 4.3+ device. Check out the app on the Google Play Store. Here is a video showing off the notifications
The app also comes with several handy filters allowing you to easily whitelist or ignore ongoing/silent notifications. You can also deactivate the notifications during games.