eBuddy Messenger - eBuddy Messenger is a legendary application for the Android version that has been present in Windows and Mac, and formerly known as Meebo.
Gajim - Full featured and easy to use Jabber client
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
CoyIM - CoyIM is a safe and secure chat client.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Empathy - Apps/Empathy - GNOME Wiki!