I have always enjoyed David Weinberger's writing (and speaking) style. He has a long-running column in KM World, and the September 2011 entry struck me: The wisdom of impractical knowledge
In the 1980s, when the idea that data, information, knowledge and wisdom formed some sort of pyramidal value chain, knowledge started to get redefined as "actionable information." This was not the first time in Western history that knowledge was tied to the practical as opposed to a purer understanding of the cosmos, but within the business world it seems to have stuck. Knowledge that does not help you make better decisions is not knowledge worth having, or possibly is not knowledge at all.
Beyond this introduction, the short form of the article is that "impractical knowledge" is actually quite helpful in the long run. People (humans) need unusual sources to help spawn new ideas - new ways of thinking about the same old problems.
This line of thinking takes you to innovation as well as to problem solving and decision making. The more external influences - no matter how unusual or "irrelevant" - the more chances you have to making lateral connections to problems and challenges you face in your life or work.
So, go out and do things you wouldn't normally do. Or do something you haven't done in ages. And look for people around you with oddball (to you) interests. You just might get lucky and that impractical knowledge will become practical in some unexpected way.
[Photo: "Impractical, yet Practical" by lildude]