Facebook recently launched a suite of social plugins for websites allowing Facebook users to interact or promote your website to their friends. The most widely used of these plugins will be the Like button as shown below:

From Facebook:
Social plugins let you see what your friends have liked, commented on or shared on sites across the web. All social plugins are extensions of Facebook and are specifically designed so none of your data is shared with the sites on which they appear.
Facebook’s social plugins are easy to use and 4W have been adding them to various clients’ websites yesterday and overnight many of them have been Liked or Recommended by quite a few people. We were certainly surprised by the numbers – much more than previous attempts to promote websites to social media such as the Add This button which we found was rarely used.
The proof of any success though will be seen in traffic statistics – it will be interesting to see over the next few weeks if this feature significantly increases traffic and revenue to our clients.
Of course website designers will now have to integrate this feature into many of our website designs.