Oh, I love this thread already. Apologies if any of these were mentioned -- I'm working with a very, very slow connection.
Ramona: The heroines of children's books are having a moment, what with Alice, Eloise, and Matilda leaping up the charts. Ramona has the same literary pedigree and spunky, vintage feel. Rae and Ray are becoming popular in the middle spot and would make a great short form of this wonderful, underused name.
Linnea: Lydia is in the a Top 100, while lovely Linnea isn't on the charts at all. Lovely and literary, Linnea is a true undiscovered gem.
Nova: I find myself recommending Nova all the time, which speaks to her versatility. Nova could be the sister of uber-popular Isabelle or ultra-obscure Thisbe. The association with astronomy gives this sleek pick an air of mystery, and the meaning, "new", is simply perfect.
Viveca: 'V'-heavy names like Vivian, Violet, Evelyn, and Eve are all the rage. Why not the elegant and far more distinctive Viveca?
Nina: Nina is a total sweet-spot pick. She's consummately international, cute for a little girl and sophisticated on a grown woman, easy to say and spell, yet consistently underused. Nina has never cracked the Top 100, despite her steady history of use.
Dahlia: Okay, I'm cheating. But how could I not mention Dahlia? Botanicals are huge right now, but Dahlia remains under the radar. With Delilah growing in popularity and sister antique flower names Lily and Violet in the Top 100, Dahlia is absolutely perfect for the parent who wants a name that's on-trend without being trendy.
Runners up: Lavinia, Virginia, Mavis, Francesca, Phaedra, Ivy, Averil, Geneva, Aisling, Briony, Mercy, Clio, and Madigan.
Reuben: A handsome biblical name, the perfect alternative to overused Benjamin and fast-falling Robert and Richard. Rue was a Nameberry hit after The Hunger Games; why not affable, wearable Reuben?
Tobias: By rights, Tobias should be a Nameberry favorite. It's a classic name with a whiff of British aristocracy and the wonderful, Western-inflected nickname Toby. I can't understand why this one doesn't get more love.
Gareth: Strong yet romantic, Gareth is the name of a knight of the Round Table. This would make a wonderful heritage choice, far more distinctive than Gavin.
Calder: Surnames are trendy, and Calder is, in my opinion, one of the very best. An artistic and sophisticated alternative to Hunter, Archer, and the rest, with the great vintage nn Cal.
Blaise: Another wonderful, on-trend name languishing in obscurity. Blaise is a saint and a philosopher; he feels at once mythic and totally modern.
Runners up: Ivan, Matthias, Luther, Dorian, Flynn, Quillan, Eamon, Cashel, Conrad, Eliam, Donovan, and Zeke.
Vega: Vega is a star - literally. I adore astronomy names, and Vega is doubtless one of the very coolest. V's are hot, as are surnames. Vega is a sleek, cross-cultural winner.
Carmen: Yes, it's more popular for girls, but with Carter and Cameron feeling passe, I could see the historically unisex Carmen gaining favor for boys as well. I love this name on either gender.
Hollis: Hollis doesn't chart for boys or girls, but it's a smart, sharp, sophisticated choice on both. Hollis splits the difference between a botanical (Holly) and a place name (Holland), and it's a surname. Why don't I see Hollis more often?
Arden: Shakespeare's Forest of Arden is a pastoral utopia, making Arden an intelligent nature name with connotations of wonder and escape. It starts with an 'A', always a favorable point, and has the popular '-en' ending. Archer is huge; why not Arden?
Sage: Sage charts for boys and girls, and though it's more often heard on girls, it's still relatively rare on either. Sage is a botanical with substance; it does double duty as a word name, meaning 'wisdom'. Sage has all the makings of a Nameberry darling, but I don't see it nearly as often as I'd expect.
Runners up: Bellamy, Cyan, Flannery, Noel/Noelle, and Sailor.
I'm looking forward to seeing everyone else's lists!
I'll give it a shot.
Boone: With Western/cowboy names like Wyatt, Levi, and Silas getting so much attention, how is Boone not in the top 1000 yet? Boone comes from the French word bon, meaning "good," and the homophone boon means "something to be thankful for; blessing; benefit." There's also American folk hero Daniel Boone to give it an air of adventure and Ian Somerhalder's Boone Carlyle from Lost to give you a pretty face to attach to the name. With the current fondness for strong, one syllable names for boys - Max, Jack, Luke, Blake - Boone really deserves some attention.
Constantine: If majestic choices like Augustus, Leopold, Sebastian, and Balthazar can make their way into many a berry's heart, why not the fabulous Constantine? Christians will appreciate the connection to Constantine the Great, the first Roman emperor to convert to Christianity. I think everyone can appreciate the connection to Constantinople and the rich cultural heritage of the Roman, Byzantine, and Ottoman empires. That aside, I just find Constantine to be really bad ass. You can't be named Constantine and not be incredibly intelligent and interesting, you know?
Eleazar: With Eli, Elijah, and Elias all well-established choices and a growing interest in elaborate Biblical choices, Eleazar should be getting more attention. It's got that zippy "Z" in there to give it some energy and make it fun. There's also Elie Wiesel. I just think it's cool.
Forest: If only Forrest Gump had been given a different name. Nature names are hot, and if you don't mind the occasional "Run, Forrest, run!", why not consider this wonderful nature name?
Gerard: A medieval favorite and now the name of the dashing Mr. Butler, this name really does have a ton of potential. It's incredibly handsome and a very strong choice.
Also Ramsey and Shepherd. *clears throat*
Allegra: It means cheerful and lively! Forget the allergy medication. I think this would make a great choice for a spring baby; it reminds me of blooming flowers, warm sunshine, and birdsong.
Cosima: Sleek and celestial, Cosima is all starry nights, silk, and velvet. It's quite a sensuous name with such a pretty sound.
I also want to nominate Delphine, Lavender, and Zipporah, even though I've run out of time for "whys" here.
Oh you guys have excellent taste! I completely agree with Boone, Delphine, Ramona, Reuben, Jocelyn, & Humphrey :) They all deserve a little more love
Amabel - a charming alternative to Annabelle/Isabelle et al. which appears to be used precisely never. There were less than 5 born in England and Wales last year, none in NI or Scotland, and I haven't checked but I don't think it's on the American list either
Bryony - a lovely flower name that I see mentioned occasionally, but it doesn't get much love
Dinah - it's so sweet, but it's never been popular, even though it's very much like Diana. It's my current love. I don't recall ever seeing it discussed here beyond a brief suggestion for a Biblical girl name or something similar
Emmeline - I'm pronouncing this EM-uh-leen, not -lyn or -line. I think this is absolutely perfect for those who love Emma or Emily but dislike their popularity and far better than hijacking a boy's name like Emmett or Emerson which I have seen. It's very vintage too, which should surely give it extra brownie points for many
Tamsin - this would be the perfect way to honour a Thomas without using Thomasina which I think can be a little too much for some people's tastes. I think perhaps people might be put off by the nn Tammy as it's rather dated.
Others neglected - Aveline, Cassandra, Flora, Marianne, Tahlia
Barnaby/Barney - just so sweet and cuddly. I think this should definitely get more love, but perhaps the dinosaur connections are putting people off?
Bertram/Bertie - I actually know two Berties IRL - a 70-something Robert nn Bertie and a 17-year-old friend of my brother Bertram nn Bertie. I never hear either Bertram or Bertie mentioned here but I think they're wonderful. I also like Bertie as a nn for Albert which is used a bit more on here, but not usually with Bertie
Darcy - for a boy, not a girl. It's just so handsome and dashing but it's popularity for girls seems to scare people off
Maxim - Max-EEM, not MAX-im. This is the only long form of Max I particularly care for and whilst Max is common enough on here this is rarely suggested as a longer form
Monty - I don't think I really ever see this mentioned. I've seen Montgomery mentioned a few times though I think of it more as being a nn for Montague, most likely as I know one, Bertram's older brother. I think they're great names for brothers! Their eldest brother is Augustus nn Gus which is far more Nameberry-approved, but I hate it! Monty's on my list just as Monty ATM and I think it could work on it's own without seeming too nickname.
Others neglected - Cassian, Dorian, Moses, Rufus, Sterling
I would say names that have been trendy in the past but aren't now. For example, Keith, which I really like.