Please read this description before buying this app.
Gizmodo.com -- "it'll pay for itself three times in one month."
SMS Touch enables users to compose SMS messages using Apple's wider landscape keyboard and send them through email without incurring SMS fees. (these messages are sent through your email program but arrive with the recipient as SMS messages).
Users can compose a text message in SMS Touch and then select the recipient's mobile phone number from their contacts. When the user hits send, SMS Touch generates an email message that is properly addressed to arrive with the recipient as an SMS message. When the recipient replies to the text message, the reply arrives in your email inbox.
Users can message up to 100 different individual recipients using SMS Touch. You can send as many text messages to these 100 people as you like. Note, SMS touch does not currently work with international (i.e., non-US) numbers.