This technique is responsible for my reading in depth about the history of shipping containers, learning just a little bit about how to do interior design, and reading a large number of gardening books. (And doing some gardening!) Among other things.
You could probably come up with something similar online. (For example, clicking "Random article" on Wikipedia and actually reading it.) But I find that if I'm at a computer, I'm more prone to revert to narrow interests. Going to the real, physical library seems to make me less distractable -- or more so, depending on how you look at it. :)