Yeah, once you know someone’s age, that can tip the gender meter, since a lot of former surnames that used to go to boys now go to girls.
Kelly used to be a girl’s name to me, but I’ve met two adult male Kellys in the last year. Now, I’d guess a young Kelly is a girl and be unsure about an adult Kelly.
There’s Gene Tierney, who was most definitely female. There’s also Jean Shepherd who was definitely male. (He was the narrator of A Christmas Story.)
I will also agree with Robin being androgynous. I went to kindergarten with a boy named Robin, and if you want to go literary, there’s Christopher Robin and Robin the Boy Wonder. I’ve also gotten mail inviting me to join the Boy Scouts and a few other boys’ organizations. The androgyny is why my user name is MsRobyn.
Robin, female
When nobody in your neighborhood can pronounce French, Jean is definitely a girl’s name, as I had to be reminded time after time while growing up.
I’ve found fairly about a 30/70 mix of males and females named Yuki, though the kanji used to write them are different.
My uncle Robin was placed in the girls’ dorm when he went to college.
Cameron and Ryan are pretty gender neutral nowadays. Also Casey, Danny/Danni, and my own name, Lindsay (although I think that could be divided into male in the UK and female in the US).
Spelling helps.
Jackie/Jacky/Jacqui- Jack, John or Jacqueline
Pat/Patty/Pattie-Patrick or Patricia
Ger/Gerry/Jerry/Jerri/Gerri- Gerald or Geraldine
Leslie/Lesley
Jamie/Jayme/Jaime
Jo/Joe/Joey-Joseph or Johanna
Sam/Sammy/Sammie/Sammi-Samuel or Samantha
Jean/Gene
Johnny/Jonni/Johnnie
Jude- could also be short for Judith.
Jules- could be a Julia or a Julius.
Ron/Ronnie- could be a Ronald or a Veronica
Makes me happy to think that the names for my 3 girls are neither the most popular nor Pat like hermaphoditic: Jacqueline, Audrey & Serena. (agnostically praying that someone doesn’t chime in that “Audrey” somehow is in the top ten names for both boys and girls in 2006)
I had a couple of tenants, Tracy and Robin, I always got them mixed, I still can’t remember which was the male or female.
I have three sibs.: Pat, Sidney and Mike, only one is female.
I also have a niece named Mondae. I’ve never run across that name anywhere else. I like it BTW.
Francis is an older name that goes either way.
Morgan
Although that seems to be swinging toward the female, as well. I actually prefer it for a boy, but like it so much I gave it as a middle name to my baby girl.
O
There is The Story Of O, female and O Henry male.
Jean is gender neutral, although I’d lean more towards a boy, and Jeanne for a girl.
As any good Harry Potter fan knows, Blaise is an androgynous name.
Remember Dana Carvey? (Is his last name Carvey 0r Carvy? 
) A male Dana.
A bunch of names have different genders in different cultures.
Someone already pointed out Jean (a man’s name in French; the woman’s name is Jeanne). Likewise there is René (the feminine is Renée) and Jocelyn (the woman’s name is Jocelyne).
Joan is a man’s name in Catalan, as are Andrea and Nicola in Italian.
Living in Quebec, I’d have to clarify whether a spoken name were Yves (a man’s name) or Eve (being pronounced the English way).
My little sister Taylor insists that it is.
When I was little, we had a family friend that was a guy named Lynn.
Vern
Joey
Danny
Jesse
I can’t believe no one said COREY yet. I have had students who were both male and female with this name.
There is a male custodian where I work named Loren. I have a male student named Dana and two boys named Taylor.
What about Stacy? I lean more toward girl when I see it but there’s a male newscaster in Pittsburgh with that name, and I’m sure other males have it too.
Not knowing whether I was a Christopher or Christine, the spammers whom my old email provider let through selling “cures” for “sexual dysfunctions” would send me 2 ads at a time–one for stuff making my penis bigger,stronger, harder, longer-lasting, and one for stuff to give me firm EE breasts.
Maybe buying and using both at the same time would have been my ticket to immortality via the Guiness Book, but probably not in the "fun"way–more like “World’s Biggest and Poorest Sap”.
We have a boy and girl in my school named Peyton and a boy named Dakota (it sounds like a girls name to me).
Kelsey can also be both.
I have known both males and females named Kim.
Others that can go either way:
Shannon, Shawn/Sean (though usually with the Sean spelling, it’s male) Stacy, Tracy, and Alex. I’ve known a Shearlie (pronounced Shirley) male, and Nashville had a longtime Mayor Beverly Briley who was male.
biometricks I know male and female Peytons and Dakotas, too.
My name’s Andrew, and I tend to use that for friends and colleagues because I’ve frequently met them at work or elsewhere where I’ve been filling out forms. However, to my family, I’ve always been Drew. There was never any question that it was as male as Bill or Dave until about five or ten years ago, people started asking why I had a girls’ name. I was quite pissed off.
I know this thread is about gender-neutral names, but I do like some of the names that are very biased one way, but used the other. Some of them are quite old-fashioned too - like men called Beverley. That was not unusual, once upon a time. Similarly, for some reason, my life has seemed to be tied up with women called Kim. That’s all well and good as a name, but I reckon it’s a brilliant man’s name. I always imagine a man with a strong character if he’s called Kim. For women, it’s just a name.