While I cannot determine any culture-independant names, the following appear to be common gender-neutral names in North America:
Ali, Ace, Ashley
Bailey, Brook
Casey
Dylan, Dakota
Emerson
Finley
Guadalupe
Hayden
Jordan, Jessie, Jamie
Kim, Kennedy, Kasey
Leslie
Morgan
N?
Ollie
Pat, Phoenix
Quinn
Ray, Riley
Sam, Sidney
Teagan, Terry
U?
Val
Willi, West
X?
Young
Zion
With some help from babynames1000.