All you need is a browser with the awesome Unity Web Player installed, and a web connection of course. You can create a character, become a citizen of virtual Quahog, and play and interact with your friends and favorite show characters.
Family Guy Online will launch exactly later this year, but you can create your character now, with the Character Creator. This is an awesome tool that allows you to create and customize your own Family Guy Online character. The character you create will be the one you play once open beta starts, and if you register now and stuff, you have a much better chance of being part of the closed beta.
More articles about Family Guy Online