The Sydney spelling most popular for girls: it's in the Top 50 on the female side. Cool for a girl, still nerdy for a guy.

A couple of decades ago, nerdy boy Sidney morphed into a polished, poised, creative, elegant girl Sydney. Sydney's been on the rise since the nineties -- it was in the Top 25 from 1999 to 2003 -- but has recently dropped out of the Top 200.