In case you have not tried Viber before, we have to tell you that you have been missing quite a lot. The app requires no registration whatsoever and is absolutely free of charge. Besides that, it has a built-in texting feature that lets you send messages to other Viber users, and the sound quality that it provides is superior to what you would get from a call placed over a cellular line. Add to all that its ability to integrate seamlessly with your device's contacts list and you have one neat little app that you will probably find yourself using more and more frequently every day.
So, if you have not done so already, grab Viber from the Android Market and see what over 12 million Viber users have been enjoying. As for all the BlackBerry owners out there, there is no need to get jealous as an official BlackBerry version of the app is also coming down the road.
Viber [Android Market link]