An application designed to solve a problem you probably had more than once:
get to the office and realize you have forgotten your mobile at home.
You can not make the phone go to the office, but you can send an SMS from another phone and activate Forgotten Phone.
When the application is activated, it will connect to Google Talk in order to
allow you to divert your calls and to send SMS (among other functions), all from
anywhere where you have access to a web browser.
Also, once activated (sending the configured text in a SMS or manually from the app), when someone text or call you, your phone will alert you opening a conversation in Google Talk and sending you the event information so you can return the call or answer the SMS immediately.
Besides this, you can also activate the phone's location service (by network or GPS if available) to receive the phone location if you are wondering where your phone are, to activate or deactivate Wifi network and to get contact numbers looking them up by name.
All this from an app that you only need to configure once and that resides in your phone (dormant and without draining its battery) waiting for your SMS.
If you need help creating a Google Talk account for your phone and activating it, you can see the attached video.