As we all know, the Search Engine Optimization field is booming day to day with new inventions and innovations. People may not know that much of what they have learned yesterday will be out of date by tomorrow. Unless one updates his knowledge by reading SEO news/articles, there is no doubt he'll lag back in the SEO race.
Note: These things have to be done after the completion of on-page SEO. Before doing these things you must be aware of your competitors who can able build a negative reputation against your company/website.
1). Community Creation in Social Networking Sites