Here is a quick link to a blog post from Jeff Bullas that lists the headlines that went viral and how you can implement some of the techniques in your own content marketing. Here is the gist of the formula:

• Create a solid mechanism that enables people to share your content on social networking websites. Remember that it isn’t always about your headline or the content it contains. It is also about the sort of people who share your content on their timelines. The sort of people sharing your content can have a big impact on your headlines going viral.
• The blog post states that David Ogilvy once wrote down 100 headlines for one advertisement. The editorial team at Upworthy creates 25 headlines for every piece of content they publish. Create multiple headlines for your blog posts and articles and then choose the most appealing one.
• There is nothing wrong in creating long headlines contrary to what is normally advocated by social media marketing experts. Even longer headlines can go viral as long as they are making the right impact.
• Try to create a sense of curiosity in your headline.
• Pak a bunch of emotion