I don't view myself as very smart, especially in comparison to the others here. I'm also not very skilled in math, nor would I say that I have a deep affection for it, so I'm sometimes surprised by how giddy I get at some of the stuff.
Calculus pretty much blows my mind, especially the idea of dividing something into an infinite amount of pieces, or series, or limits. I'm not very good at it, and I only know the very very basics of it all, but I love the idea. Things like center of mass expressed via integrals makes my face melt because it's like a completely new view on what's really happening on something I thought I understood.
Any simple visual diagrams proving the Pythagorean Theorem makes me feel funny.
When I first learned about Euler's Identity, I flipped out.
Learning about the relationship between Maxwell's equations and the speed of light blew my mind too.
I'm sometimes bummed out when people don't react as much as I'd like about the stuff, but I'm a poor describer.
Otherwise, some other things:
Crazy drumming makes me hop around in my seat like a child. Maybe "crazy drumming" isn't the right wording, but just any drumming I enjoy. I really get into it. I broke the armrest on my car because I was smashing on it, copying the drum fill that leads into the chorus of Toto's Africa. But I think my alienation about this stems more from the widely differing tastes in my friends' and my music, so there's rarely ever a time where I'll show my friends some fun drumming and they go, "Wow! Yeah, that was awesome!"
I'm also a pacer-thinker. People often tell me that I should sit, but I always explain that I have to walk.
I get my kicks naming my hard drive partitions after fictional paradises. Also, when simulating network topographies, I like to name the devices in a manner so that it resembles a family tree of some famous people or some fictional character. Everyone else is unamused.
I like rain and distant thunder sounds. I live at a pretty high elevation, so drainage isn't much of a worry for me. RainyMood isn't the same. It also helps I'm more of an indoor person anyway, so rain gives me a wonderful excuse to do what I normally do.