From the maker of handy iPhone landscape typing program TouchType, SMS Touch is an iPhone app that allows users to send unlimited text messages without paying for an SMS plan.
It's a clever idea. Avoid that $15 unlimited texting plan from AT&T by using your free email to send SMS messages. With SMS Touch, you can write an email (complete with the landscape-style keyboard and spellcheck functionality) and send it as an SMS to anyone in your phonebook. When they respond to your text message, instead of coming back to your phone as a chargeable SMS, the message actually arrives in your email.
In other words, you can send SMS messages while all the while communicating in email. Priced at $5, part of that fee goes to ongoing backend support for the program. And if you're interested, it'll pay for itself three times in one month anyway. [SMS Touch]