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.
About.com – How many times have you tried to do something and needed instructions? You Google it and it brings up how-tos from About.com. Well, you can contribute to this site with some of the how-tos for your niche and get traffic from it. Additional tip – there is an About.com Forum where you can be helpful to people in need and get additional traffic to your blog.

You had to know social media would be on the list. I generally recommend that a site only have a presence on 2-3 social networks, at least while they’re small. It’s a lot of work to maintain, engage, and update a social network profile, and keep its messaging consistent with your branding. You can always spay someone to do it for you, but then it’s not a free traffic source, is it?

A few links down and I've noticed that Brian has a link from WordPress.org. Not bad! Turns out that his content has been referenced within one of WordPress's codex posts. If I were to reach out and offer some additional insight, citing one of my articles, there's a chance I could bag a similar link, especially considering they have a 'Useful Resources' section.
If you publish whitepapers or offer downloadable PDF guides, for example, you should be tagging the embedded hyperlinks with UTM campaign parameters. You’d never even contemplate launching an email marketing campaign without campaign tracking (I hope), so why would you distribute any other kind of freebie without similarly tracking its success? In some ways this is even more important, since these kinds of downloadables often have a longevity not seen in a single email campaign. Here’s an example of a properly tagged URL which we would embed as a link:
Encourage incoming links. Google prioritises sites that have a lot of incoming links, especially from other trustworthy sites. Encourage clients, friends, family members, partners, suppliers, industry mavens and friendly fellow bloggers to link to your site. The more incoming links you have the higher your site will rank. But beware SEO snake oil salesmen who try to trick Google with spammy links from low-reputation sites. Some links can actually damage your SEO.
Hey James, I LOLed at your comment. In a good way of course. What do you mean you knew about 3 things!? You better get to work then. Just kiddin'. Glad you liked the list and hope you will put it to use. And if you do, I really hope to hear some feedback on how it worked for you. These tips are awesome for websites like those, I have some of those. You should definitely give this list a go, I first tested all these on my main niche site and then on my blog. I can tell you that these sources can make miracles if they are used right.
Secure (https) to non-secure sites (http): Since Google began emphasizing the importance of having a secure site, more websites are securely hosted, as indicated by the “https” in their URLs. Per the security protocol, however, any traffic going from a secure site to a non-secure site will not pass referral information. For this issue, you can correct by updating your site to be secure through a third-party SSL certificate.