If the little Facebook chat window is not enough for your communicative needs, try Chit Chat for Facebook instead.
Chit Chat for Facebook is a simple desktop app that lets you use the Facebook chat without even having to open the web browser. It looks and works like a regular chat client, with a particular resemblance to Windows Live Messenger.
Once you log in with your Facebook credentials, Chit Chat for Facebook will display your list of contacts, separated by online and offline. There’s no option to create groups though. Starting a conversation is as easy as double clicking a contact, and a right click will reveal a context menu with options to send an email to that person or write on his/her wall. Other interesting features are support to log chats, and online/offline notifications.
On the downside, the truth is that Chit Chat for Facebook is not very reliable and felt quite unstable during our tests. It messes with the online chat tool on the Facebook website, takes a while to show online contacts and its constant reminders to promote it on your account quickly become annoying.
Chit Chat for Facebook could turn into a handy desktop alterntive for Facebook chat, but it still needs some development.