Brankica, Very comprehensive list there. Can't think of anything else :D RT! I think the traffic sources that I hardly use is answering questions. I find that traffic conversion there is poor for me, so I don't focus too much on it. I think of all those in the list, focus on those that gives you the best kind of traffic. Forums can be a particularly useful one especially when people are there asking for help. Answering their questions and giving them a link that benefits their query is one good way of getting the right kind of traffic.
The term “organic traffic” is used for referring to the visitors that land on your website as a result of unpaid (“organic”) search results. Organic traffic is the opposite of paid traffic, which defines the visits generated by paid ads. Visitors who are considered organic find your website after using a search engine like Google or Bing, so they are not “referred” by any other website.