I have been using Followerwonk for a number of years for influencer identification, content promotion planning, and content idea generation.
I really love the ability to search user bios for specific keywords, compare users, find like users, and see what each person shares.
Additionally, it's great for generating content ideas. By understanding what your audience is already sharing and what topics they tend to discuss, you can more appropriate plan your own content strategy.
A big challenge in content marketing is creating content that drives results. The more data you have around your audience and the more information you can gather, the more likely you are to create content that truly resonates with your audience.