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
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.