Something you're just good at with minimal effort and/or you learned much more quickly than average.
For me, it's paper snowflakes. My brain just seems to effortlessly figure out what cuts to make to the paper wedge to make it turn out exactly how I want it. Largely useless, but good fun and was a much-needed ego boost when I was a kid :]
I have really good hearing and I'm good at guessing pronunciation of people's names in certain languages.
I have fond memories of listening to conversations at the other end of the table at family gatherings. If we're out with a bunch if people, I'll listen to the various conversations.