Soren is actually high on my shortlist for both boys and girls. I love it, though I worry it's going to become too popular for my taste ;-) Another similar name I really like for both sexes is Rowan, which has a similar feel to me. Rowan is on the rise in popularity too- #450 in the US for girls, and #366 for boys.
I've been a little bit obsessed with names and naming for the last few years. My favorite site is the Baby Name Wizard, which lets you look at the frequency of different names and portions of names over the past 100+ years: http://www.babynamewizard.com
. The author of that site also runs an excellent blog on naming: http://www.babynamewizard.com/blog
I'm particularly fascinated by how, seemingly out of nowhere, certain names and naming sounds will become popular. Sometimes you can find a clear link to a celebrity name or something like that. But not usually. How to explain the explosion of names for boys that end in 'n'? They now account for 30% of all boys born in the US. And of course, I love the sound too
I started thinking about the name Aden for a boy a number of years ago, long before Aiden/Aden/etc became one of the most popular names around! Weird.