The basic concept of location-based mobile phone messaging is that you can send a text message to someone's cell phone and they will receive the SMS message only when they enter into the exact location you specify. How can this be useful? Let's say you're up really late working and you want your co-worker to pick up some donuts in the morning on their way to the office.

Using a service called JotYou, you can send a message to your friend's cell phone and have them receive it just before they get to the donut shop.

You could use the service to remind yourself to do things when you drive by specific locations in a city. Next time you need to pick up some groceries from the local supermarket on the way home, create a JotYou message that will send you a text message when you drive near the supermarket.

JotYou also has a tracking feature that you can turn on for more fun stuff like games, events, and contests. The organizer of the event can create a tracking group and track the positions and times of all of the participants as the event unfolds.

To get started with JotYou, you need to first create a free account. Once you do that, it's a simple process and fun to play around with. First you'll need to install the JotYou software onto your mobile phone. You can then send messages from your computer or from your cell phone.

The cool thing about this program is that it uses Google Maps to pick the location and set the area for the message to be delivered. First you drag the little marker close to the city where you want to send the message. You'll then be zoomed in on a part of the city with a red circle around the marker.

You can zoom in or out to the exact location you're looking for and then press the smaller or larger buttons that are below the map. You can make the circle smaller, but there's a minimum size that it can go. Obviously, it must determine locations based on cell phone towers and that's the reason why it can't be too small an area. According to the map, the radius of the circle is about .6 miles.

You then simply fill out who you want to send it to, the time, when it message should expire, and the actual message.

If you enable tracking and everyone accepts, then you can actually plot the path across the city or town that the person traveled using Google Maps. Which would perhaps dissuade people from accepting! Nevertheless, JotYou is a Mobile Web app with a lot of potential uses.