Check what's the latest trends on your niche and create articles about it. You can check the trends through Google trends, and also check what's hash tags in your niche trending on twitter. So, when you tweet it, you can use trending hashtags in your topic.
Put some twists on your topic such as including controversial topics in it, or perhaps comparison of products in your niche that you're promoting on your site.
You could also go to Yahoo answers and check what's hot in your niche/topic and write an article about it, then share it there.