Are social networking sites still useful for you?

The number of people using Facebook has hit the 500 million mark, meaning one in every 14 people on the planet has now signed up to the online social-networking service.

"As of this morning, 500 million people all around the world are actively using Facebook to stay connected with their friends and the people around them," Facebook founder Mark Zuckerberg said in a blog post.

"This is an important milestone for all of you who have helped spread Facebook around the world."

Are social networking sites still useful for you? Here is the latest selection of Your Views: