Capture - A great free screen capture utility that allows you to capture either a window or the desktop and save it to either a file or the clipboard.

Empathy - Apps/Empathy - GNOME Wiki!

Bigbee - Connect with anyone, anywhere.

Pidgin - Pidgin is an easy to use and free chat client used by millions. Connect to AIM, MSN, Yahoo, and more chat networks all at once.

Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.

Trillian - Trillian is a decentralized and federated instant messaging platform that lets your whole company send private and group messages, keep tabs on what co-workers are doing, share files, and much more.