Freya has long been popular in the U.K. but has only taken off in the US in the last decade, along with the entire category of mythological names. Derived from the Old Norse name Freyja, meaning "Lady, noble woman", Freya is the name of the Norse goddess of love, beauty, and fertility.

Emerson is a dignified, somewhat serious name associated with transcendental thinker Ralph Waldo Emerson. Much more popular now for girls since Desperate Housewife Teri Hatcher used it for her daughter, it is definitely still a viable boys name.

Ruby could be a short form of the Biblical name Reuben and especially its streamlined form, Ruben. As a gemstone name, it's currently enjoying a fresh boom of popularity for girls – nearing the US Top 50 for the first time in almost a century.

Harper got its start as a celebrity baby name when Paul Simon chose it for his now-grown son. Since then, other famous parents have followed suit: musician Tim Finn and actor Cecilia Peck both have sons called Harper.

Very popular surname choice — it's in the Boys' Top 100 — beginning to catch on for girls. First female association: novelist Carson McCullers.