Everything on Wikipedia and other Wikis has a resource part. So if the image's resource is your blog (and I am talking about useful and good images, not just anything) you will get traffic. I explained in the post how it generally works for a travel site for example. It works better for some niches than others but creative people can make everything work for them.
Thanks, John :) You are right about the forum, if you are answering some questions that you don't really get into but are only trying to self promote, people can tell. That is why genuine people have great traffic coming from forums, cause everyone can see they are trying to help. I have a rule for myself, where ever I try to build traffic and establish myself as a person that want to help, I never post links all the time. I only do so if it is really related to the question. I think that is why I have success with it. I think you could rock with Reddit because your art is great. Can't wait to see what results will you have with it. I am also thinking that Digg and Flicks might me good solutions for you.
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.