I think SMO, would be the best niche marketing options for 2013. Social Media is the most effective marketing technique which is continuously growing over. Most of the people are on the popular Social Media sites. Facebook, Twitter, Pinterest users are growing rapidly. It is the best option for targeted traffic.
Mobile advertising and Video Marketing for me. I have seen a lot of marketing plans for next year and most of it includes mobile advertising since people are more attached with their phones. Also one rising trend is the video Marketing , where businesses produces videos and integrate them with email marketing. I want to know more about it soon.