Adium is a popular and, probably, the best instant messaging client for you Mac at the moment. It supports a great number of services, including MSN, Yahoo! and AOL Instant Messenger, Google and Live Journal Talk, Facebook Chat, Twitter, ICQ, Bonjour, etc. Moreover, the application offers you a variety of options and high customizability; you will be able to adjust almost everything from the app's appearance to file transfer parameters.
Among the numerous features of the application, I would emphasize Tabbed Messaging and Encrypted Messaging. Adium allows you to combine multiple chats into a number of windows with tabs, which make your work more convenient and gives you more free screen volume. You can enable the option in General Preferences. Also, there you are able to set the program organize tabs into new windows by group. Due to the Off-the-Record Messaging support Adium allows you to send encrypted messages. Therefore you can be sure that no one will read your private message but your recipient and you.
In addition to all above, Adium gratifies you with cute interface and offers a lot of 'Xtras': sounds, emoticons, images, styles and many more. By the way, it is translated into 27 languages and some more localizations are in progress.
Unfortunately, Adium does not support voice and video chat, which, to my mind, is the only disadvantage of the program.
v1.5 [Jan 18, 2012]
Updated libpurple to 2.10.9, fixing many security issues.
Updated the PSMTabBarControl framework, used in Adium for tabs:
-Fixed an issue which occurred when dragging a conversation window into an existing tabbed conversation window and which caused Adium to become unresponsive. (#16281)
-Fixed an issue causing tabs/windows to disappear when being dragged. (#15414, #15518, #15822, #16305)
-Fixed an issue where tabs would disappear after several hours. (#16262)
-Fixed visual glitches on bottom tabs seen on Retina Displays. (#16074)
-Tabs now use all the space in the tab bar. (#7690)
-Fixed tabs not being spoken by VoiceOver. (#16088)
Fixed a problem that could cause high CPU load when a connection is lost. (#16431)
Fixed a bug that can cause disconnects when using a Retina Mac with an external screen. (Johannes Loepelmann) (#16552)
Fixed an issue causing to Adium to connect accounts during PowerNap. (Mayur Pawashe) (#16249)
Fixed idle checks to no longer use the proximity sensor of modern Macs. (Christopher Loessl)
Fixed dates in the chat log viewer not showing up for very old logs (2006 and earlier). (#16554)
Security: Enabled a number of TLS ciphers using SHA256.
Fixed connecting to servers with outdated TLS support using the unofficial SIPE plugin. (Michael Lamb) (#16550) The fix only applies to OS X 10.9, one for OS X 10.8.5 should follow.
Fixed vertical placement of the unread count in tabs. (#16318)
Fixed a misbehaving link in the Setup Wizard. (#16587)
