Years ago when ICQ was invented me and a lot of others were to be found on it almost constantly. Well, not when you weren't at home of course - that had not been invented yet. Nowadays you can easily find you in an office with installation restrictions. Meebo will help you. You can login to several messaging platforms at the same time and chat through their AJAX built webinterface. As AJAX provides you with the look and feel of a local app, so does Meebo. I loved it instantly. Link : Meebo