In a nutshell...

Although everyone now needs to stake their claim on Facebook and at least list "directory information", a Facebook presence in itself itself is not generally going to drive traffic to your site, unless it is unfortunate enough to feature in a "viral" posting because an employee inadvertently pressed "send" with a particularly embarrassing email. However, there is no denying that Facebook needs to be watched carefully for signs of breakthroughs that could make it relevant to your business and site promotion. Most Facebook users will try and avoid commercials and commercial messages, and actively resent being "tricked" into clicking on commercial links. Persuading FB users to click on "like" links that placed thoughtfully on your website is about as good as it presently gets.

• More than 900 million active users
• More than 50% of active users log on to Facebook in any given day
• Average user has 130 friends

Twitter is more interesting in many ways than Facebook, as it specifically acts as a "barker" channel to direct followers to sites of mutual interest around the web: The succinct nature of Tweets keeps any message simple and concise. 

• Now 105,779,710 registered users.
• New accounts are signing up at the rate of 200,000 per day.

Other share tags

There are many other social media/link sharing sites that can be invoked... here are some that you can explore them from the Share button on the left edge of this page:-