As some people have already said RSS feeds and customized news apps (Pulse, FlipBoard, et al) in niche content marketing spaces is where most people start from a high level point of view, but then you really have to drill down to quality of posts (is it releveant - +Gary Vaynerchuk
's idea of context), frequency of posts (the F.R.Y. model), and is it something that can be quickly and easily adapted/implemented for one's own industry (best practices).
When you have information overload across multiple channels you start to pick up on common threads and trending topics without needing expensive sentiment analysis software or even free ones (Social Mention) for that matter. Ultimately, you start with your passions, job function/responsibilities, industry insight and trends and work your way backwards.