ILoveIM is a free web based instant messenger. Using this, you can connect to multiple chat networks at the same time.
ILoveIM supports following chat networks:
Best part about ILoveIM is that it is completely web-based, so you do not need to download or install anything, and can use it from anywhere.
To use ILoveIM, just go to its website, and provide your login details for all the chat networks that you need to connect. ILoveIM will encrypt your password using 1024-bit RSA keys, and then connect you to all the networks.
As soon as you are connected, you will see your buddy window. It has a nicely integrated buddy list window in which you can see your contacts from multiple networks in tabbed form. Just click on the tab to see buddies for that network.
ILoveIM is simple to use, and completely free. Try out ILoveIM here.