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.
Talk360 - Talk360 is a best-in-class communication utility that offers a convenient way to connect with loved ones globally.
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.
aTalk - An encrypted instant messaging with video call and GPS features for android.
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
FluffyChat - Open. Nonprofit. Cute ?