Really great and free service where you can chat using a bunch of services like Skype or Google Talk within your web browser, meaning you don't need to install anything on your computer.
This well kept secret surfaced just recently. All Apple devices running iOS 7 have a pretty darn well hidden Easter egg. Just follow this step-by-step instructions carefully and the very first Mac OS version 1 will appear on your iPhone or iPad. How freaking awesome is that?