There are a number of things that pique curiosity within me.
Some of them are trivial; like gardening, hermit crabs, dogs- the normal things.
But, in particular i'm very interested in how theories and "tall-tales" come about. I love listening to people tell stories, especially those that have an aura of mystery to them. Historical ones in particular tend to catch my attention, like, the uses of witch doctors in some cultures, and why other cultures have weird customs they hand onto. To me, it's like learning about an entirely different world, but it has that realistic feel because parts of these stories, if not all, do exist. This ties in a lot to psychology, and the human-reaction, which is why books like "Lord of the Flies" by William Golding interest me. It's an entirely realistic situation that is capable of happening, and explains how the human psyche can change depending on environment.
In summary: Historical theories dealing with the human reaction really interest me. For example, the idea that the human race has a collective unconscious because a lot of societies associate the color white with purity, and red with destruction and war.