One that I realized quite quickly, I have an uncomfortably strong level of empathy. Or more accurately, a strong discomfort towards emotional disharmony in others. The strongest is in strong arguments or social awkwardness. I can barely stand to watch those intentionally awkward scenes in sitcoms and movies.

I have a preternatural ability to see what others are trying to say. This comes out in two ways. One, if someone is talking to me, and they make an error, my brain will autotranslate. So if they said brother and meant father, I will hear what they meant. Sometimes I don't notice this translation until they point out an error they made. And then I'll be able to recall specifically what they said. The other way it comes out is I can spot miscommunication very easily. If two people are having a "who's on first" moment, I'll see exactly where the confusion is, and what needs to be said to fix it. It's awesome and weird.

Both of the previous items cause me to have a natural urge to resolve any conflict going on, trying to act as mediator.

Like some here, I think I have mild number synethesia. Mental math sometimes has a visual component, with numbers splitting and merging. Additionally, numbers...um....look a certain way. So the number 15 looks really 3-ish and really 5-ish. It's also a very sturdy, compact number (because it fits into 60 so well.) The lower numbers also have an aesthetic, usually based on how divisible they are or how common a divisor they are. So, 2,3,4,12,60 are all pretty but 31 or 57 are ugly. Higher numbers blur a bit for me. This may be a heuristic for how easily my mind manipulates those numbers.

Also, and with the main population I feel like an oddity for this, I derive significant pleasure from completing math problems. I imagine many others here do too.