Google Voice offers low-cost international voice calls and unlimited free text messages for a unique Google Voice phone number. There is also option of group text messaging, “improved” text message notifications and offline voicemail.
Send unlimited text, photo, audio messages to anyone in the world, as long as both of you are connected to the Internet. It is hugely popular and multi-platform (talks to your iOS and BlackBerry friends).
ICQ Mobile for Android
ICQ for Android lets you send unlimited messages for free, chat with ICQ, Facebook, and Google Talk friends, and read messages offline.
IMO Instant supports instant messaging across an impressive 11 networks (both popular and relatively obscure) including MSN, Yahoo!, AIM/ICQ, Google Talk, Myspace, Skype, Facebook,Jabber, imo, VKontakte, and Hyves.
The Android video chat app supports group video, voice calls, and instant messaging, across iOS, OSX, Android, and Windows. You can practically video chat with anyone.
Skype is “the best” communication app for Android, but it’s one of those tools that I will continue to use because other people use it, too, and so it’s often the quickest way to get in touch with certain people.
GO SMS Pro
Go SMS Pro is the SMS/MMS app for power Android users. You can send “short” messages containing text, voice, doodles, and photos. You can also customize themes, messages, and folders for storage.