While the text messaging app on the iPhone is cool looking and well designed, it's also expensive to use if you are a serial texter and you don't have the unlimited texting plan. Happily, there is now a txtDrop is offering a free messaging service over the web, so you can open it in Safari and text all you want for free. They even have a special version that is designed for the iPhone. Granted, the interface is not as nice as the built-in messaging client on the iPhone, but it does have the advantage of being free.