Flamingo is a beautiful, native instant messaging client for OS X that supports Hangouts/Gtalk and XMPP.
Important: As of April 30, 2015, Flamingo will no longer work with Facebook chat. This is due to Facebook shutting down their XMPP API. Read more about the change here: http://blog.flamingo.im/post/115085201650/facebook-shutting-down-xmpp-access-on-april-30th Highlights All-in-One design. Buddies, conversations, and chats in a single window. Multiple, detachable chats in a single window. Inline previews for images, videos, and tweets. Supports CloudApp, Droplr, Instagram, and YouTube. File transfer via direct connection (compatible with Messages, Adium, and other clients), CloudApp, and Droplr. Reply to messages right from the notification bubble in OS X 10.9. Full conversation history browser with fast message search and many filtering options.
Note: Due to service limitations, Flamingo does not support group, video, and audio chats in Hangouts/Gtalk, and MUC (Multi User Chat) for XMPP is not supported.