Great, simple app if you can't find your phone! Also can be used to alert you of an emergency. Just give someone the word/phrase you define in the settings and instruct them to send you a text if they are ever in an emergency. You will be immediately alerted and able to see who sent the text.
How does it work? This app will sound an alarm when it receives a text consisting of a phrase or word you define. This can be any combination of numbers and letters. The alarm will sound even if your phone is in silent mode, but once the alarm has finished: your phone will return to the mode it was previously in.
Note: even if no one else is around with a phone you can send a text message to your phone via e-mail. Visit your wireless carrier's website to find out how.