What Apps Allows You to Text SMS MMS?

Handcent
Handcent is a free app available for many Android phones. It is available in the Android Market for download at any time. One unique feature is Handcent's free type-to-voice speech aspect. Any text received or sent can be read aloud by the app over the phone's speaker.
ChompSMS
ChompSMS is a SMS and MMS messaging service for Android that is free to download in the Android Market. Chomp also offers Chomp Credits, which are purchasable points that you can use if your cell phone provider charges too much for texting. Chomp Credits circumnavigate the cell phone provider's text fees, making it so the only fee a user pays is the cheaper Chomp Credit fee.
GoSMSPro
Go is a free app available in the Android Market. Along with being both an SMS and MMS platform, Go offers downloadable themes and skins.
iRealSMS
iReal is an SMS and MMS app developed for iPhones. It offers quick-reply pop-ups and an attractive, streamlined interface. iReal also comes equipped with a search feature, which allows users to search all past text messages by title, contact, and subject. The iPhone must be jailbroken, or made to run none-Apple approved applications.
BiteSMS
Bite is an iPhone SMS and MMS app that is free to download and comes with a 14-day trail period. Credits can be purchased to send texts with Bite or a full-time, unending subscription to the service is available for purchase. Both iPhone texting apps are meant for 'jailbroken' devices, those enabled to run apps not approved by Apple.