Twitter’s service allows you to send messages to an address and have them echoed to your circle of friends. This would be unremarkable except that Twitter is mostly used between cellphones, creating a sort of broadcast nightmare if your circle of friends includes only one idiot.
I have several acquaintances who talk about signing up for twitter and sending it periodic updates, only have one idiot join the group and ruin it for everyone. One of my colleagues used Twitter to update his family on the status of his wife who was in labor with their latest child. That was the most useful thing I’d heard anyone use Twitter for until now, and frankly, that’s not a business model. If it’s instant messaging it’s living in a crowded market. If it’s broadcast mobile messaging it’s not useful enough yet.
However Twitter’s API is pretty dead simple, and I’ve just noticed someone with a very traditional web application using Twitter to enable data entry from a mobile phone. The application is the entirely ordinary "My Mile Marker", a service that lets you track your gas mileage. If your car isn’t new enough to do this itself, or you can’t afford to put a pen and paper in your glovebox, this is the service for you. However since most people don’t have in-car-Internet-service, there’s a real challenge: how do you get your mileage into the web application?
The answer is to use the Twitter API to let people enter it from their cellphones while they’re still at the pump. Since that’s assumed to be unsafe, they probably will want you to do it from inside your car. It’s simple, really. You tell the Mile Marker service your mobile phone number, and then when you send a text message to My Mile Marker it can recognize you from your incoming phone number attached to the message.
Using APIs like Twitter to process incoming text messages is a bit of a hack designed to glom onto Twitter’s hipness, but it works. The use of cellphones as tiny, ubiquitous data entry tools in the hands of the public is likely to be incredibly useful for years to come.