GeoMessaging is an easy way to automatically send a message to one or more contacts when your iPhone crosses a selected location on the map.

GeoMessaging runs in the background on iOS 4 devices but is still fully compatible with iOS 3.

Enter your message (what), touch the trigger perimeter on the map (where), and choose your recipients (who). Configure GeoMessaging to use your GMail, Hotmail, Yahoo, or MobileMe account.

Once GeoMessaging is triggered you will get an alert and an email is sent out to your recipients.

* Avoid texting-and-driving. Ever find yourself already driving and remembering you should have sent that message before you got in the car? Set up a GeoMessaging and let it send out your message telling your loved one you just left work.

* Notify someone that you're on the way or that you're almost there. Put a GeoMessaging message around the cinema metro station to tell your friends to save you a seat.

* Send yourself a reminder of when you performed an activity in a certain location. Wonder what time you crossed the bridge during your biking run? GeoMessaging it and you'll have a timestamped message in your inbox.

* Text-and-bike. Whether on a bicycle or motorcycle you can pre-set a message to your roommates telling them to save you some pizza because you are only a few blocks away.

Cool Tip: Most cellphone providers offer an email-to-text-message gateway. For example, AT&T is phone@txt.att.net, Verizon is phone@vtext.com, and Sprint is phone@messaging.sprintpcs.com. Use the addresses to send text messages to your recipients' phones. Save these addresses in your iPhone's Address Book and it will be readily accessible in GeoMessaging.

Remember that continued use of GPS running in the background can dramatically decrease battery life. GeoMessaging only uses GPS when you activate it. Once you trigger the message, it stops tracking your location (consequently minimizing use of the battery).