I would like to recommend an Android application which is totally free to download and use. I personally used this App on my mobile and found it very interesting and useful. The app name is Last Message and this app is very useful in the situation when your mobile battery has been depleted. It automically warn your friends and loved one that you may not be in contact once the battery has been die.
Here is a link to that application Log in to see links
Hope you will find this application useful. Try it and give me your reviews