This one comes up in philosophical discussions of ethics all the time: Sorting Pebbles into Correct Heaps
I end up referring to right vs right' a lot. Especially w.r.t. ethical naturalism. Though now that I think of it, the actual content there might have been in a follow-up post.
Followup to: The Most Important Thing You Learned
What's the most frequently useful thing you've learned on OB - not the most memorable or most valuable, but the thing you use most often? What influences your behavior, factors in more than one decision? Please give a concrete example if you can. This isn't limited to archetypally "mundane" activities: if your daily life involves difficult research or arguing with philosophers, go ahead and describe that too.