Overwolf is a free client that gives you access to several sites while you are playing games. It allows you to voice-chat and text-chat through Skype, check your Facebook news and feeds, upload screenshots and execute many other actions. The program installs its own web browser that will let you access any site you want to enter. It also allows to use your web camera to take live shots that you can share then through Facebook. You can also choose to take a snapshot of your screen, and share with others while you are playing a game (for example, to show someone that you finished a level).
The program includes a link to call Ventrilo, a free voice chat client that you can install in your LAN, no matter what operating system that you are using. If you click on the central point of the interface, you will see a series of common places you may need to visit while you are playing. All you will have to do is to click on the right buttons.
The download link will let you save on your disk an installer. Once you run it, it will download the rest of the files from the Internet. You will need 15.8 Mb. of disk space in total.