WhatsApp is an iPhone and Android messaging app which allows you to exchange messages without having to pay for SMS.
Kik is way more than just messaging. It’s the easiest way to connect with your friends, stay in the loop, and explore – all through chat. No phone numbers, just pick a username.
textPlus is the best way to send unlimited text messages from your android, iPhone, iPod, kindle, and windows devices with your textPlus phone number free and calling for just pennies.
Talkatone gives you free calls, text messages, real-time location sharing and picture sharing to Facebook and Google friends, or any phone number in US.
XendApp provides a messaging gateway for reaching public or internal users through applications for a variety of devices. Messages can be sent directly from http://xendapp.com web site or through any of the existing web services that the web site have.This app doesn't have any features at the moment.