Viber, the popular VoIP app previously available only to iPhone users, will begin rolling out its beta version for Android this week. Viber allows users to make phone calls over 3G and WiFi connections (no word yet on 4G support) to other Viber users. The app also supports free text messaging through its interface. With a free Viber account you'll have "unlimited" calling and texting to any fellow Viber subscriber on either Android or iPhone. (The service does use data instead of voice, so Viber is only as "unlimited" as your data plan.)
Viber says that it has added features unique to Android, including a full call screen, pop-up text message notifications, integration with your phone's call and messaging logs, and the ability to set Viber as your default dialer. Remember, the app is still in beta, so hit the source link to sign up on Viber's website to receive an invitation to download.