NimBuzz

Using multiple instant messengers at the same time is one of the latest trends so many users can now chat on Google Talk, Yahoo Messenger and Windows Live Messenger simultaneously.
To aggregate all those accounts and use a single interface for all the services you can try a tool like Nimbuzz. This application it is not only able to handle multiple messenger accounts at the same time, but it can also provide calls to mobile phones straight from your computer.
When it comes to the GUI, Nimbuzz is pretty user friendly, with all the features easily accessible. Also, setting up an account takes only a couple of moments, while getting used to its look is just a matter of minutes.
The contact list is similar to the ones seen in so many other instant messengers out there, so you can add new friends, open a conversation tab or set a status message. Nimbuzz also enables you to quickly send files to your chat buddies or start a video call directly from the main window of the application.
Just as expected, the settings menu is very rich, but this is a plus because Nimbuzz enables users to configure audio and video settings in detail. If you want to keep track of all conversations, simply activate the chat history.
Overall, Nimbuzz is one of the best multi-protocol software solutions out there as it provides a single interface for all instant messengers you have installed onto your computer. Also, the phone calling ability is a definitely an asset that can make this application a keeper.