Social networking to promote services

While browsing facebook I found that many travel companies were using this social network to promote events and charities. I personally feel this is really a good idea. Social networking is surely becoming popular to promote products are services. You can see the following companies using social networking to promote their services like – laterooms, lastminute.com,expedia, eight hotels etc. I keep exploring various types of social media and was surprised to learn how various individuals and organizations are using it, not just for themselves, but to benefit others.