You've probably heard of (and seen) the fake images of Android 4.4 leaks that contained very nice themed status bar to the app which was actually used. Though this all was faked, you can achieve and install this mod for your Android device and adjust your status bar with all the apps you're using!
First, let's take a look on some fake leaked pictures of Android 4.4:
As you can see, if you look closely - the status bar is themed according to the used application: for messaging the status bar turns green, for dialer it turns to be blue. This feature, though it's very nice, hasn't been added to the Android KitKat (as we know now) but there have been some mods that can actually do this using the Xposed Framework:
If you check the status bar, you can see it turned green if the Google Play has been opened and stays transparent in the homescreen. Basically, all you need to have for this mode is to have your Android device rooted.
To install the mod, you need have (expect root acces) the Xposed Framework, which is framework that allows you to modify your system without modding APk files or flashing. If you don't have Xposed Framework yet, check THIS post.
Mode should work on all JellyBean and KitKat devices. If you can't see the mode working on your 4.1+ Android device, wait a minute or two - the module will be delayed for about 1-2 minutes. This is a limitation in sendOrderedBroadcast for Android applications.