Ah yes. To me (to my productivity's detriment...) quite often when I visit Wikipedia it becomes a learning adventure. From one thing you can hop to the other, finding out all sorts of interesting and obscure things. To a curious mind like mine, Wikipedia is heaven!
For myself, I would broaden this and say that almost every link I visit on HN, or every forum post I read leads to more than 1 additional link. Thus three windows of Chrome open with 10+ tabs each :)
I find this drill-down effect to be quite illuminating, if not productive. Strangely, it seems to provide both depth and breadth of topics in relatively equal measures.
