Here's a whizzy little Google tool for brainstorming ideas for articles and series of articles. Just stick something in the Google searchbar, and then when it comes up with all the links, click on "more options" and scroll down to the wonderwheel. A bit like Tony Buzan's mind mapping, this magical bit of techno-tweakery will spark off so many more ideas if you simply click on one of the arms of mind map and then continue exploring.
Warning. This is hellishly addictive. Before you know it, you're digging so far down and so deep you've forgotten what the original series was about. A bit like reading the dictionary.