Are online social media sites such as Wikipedia, reliable sources of information?

The link below provides good overview of the reliability of information on Wikipedia. The general consensus I believe is that topic with which many people are familiar with will be more accurate than some esoteric ones. For some highly specialized subjects you might not find any information at all, because people contributing to Wikipedia are statistically biased as a sample of human population – they are all "familiar with computer and Internet and are willing to actually bother contributing the content".