In Wyrd Sisters an actor who plays a girl too well was asked whether he by chance has some elf up in the bloodline.
Parodied in John Brosnan's Have Demon, Will Travel where elves are an entire race of Camp Gays.
The two principle characters of the Nightrunner books are Aurenfaie. Both are repeatedly described as pretty, and Seregil disguises himself as a woman without much difficulty.
Elves in Quantum Gravity tend to be thin and delicate-looking. Do not mistake this for weak. Elves are still fulfilling the archer archetype fairly often, and the author does recognize how much strength it takes to pull a decent-to-large-sized bow back.
In A.R.R.R. Roberts' parody of The Hobbit, The Soddit, Wood Elves and High Elves become Wild Elves and Coward Elves. The accompanying illustration makes it clear that the Wild Elves are based on Oscar Wilde, and the Coward Elves on Noël Coward.
Elven deities in Dungeons & Dragons are often noted to be "androgynous" in looks; the artist responsible for the picture of chief elf god Corellon Larethian from the Deities and Demigods sourcebook took this to its logical conclusion with a totally FABULOUS rendition◊ (two words: rainbow eyeliner).
The Elves in Small World are depicted as overly thin, androgynous types carrying baskets of flowers.
Blood elves and high elves (but not night elves) in World of Warcraft. If a player-character blood elf jumps, there's a chance he will do a pirouette in mid-jump, regardless of gender. Joked about at length, including the blood elf male flirt, "don't you wish your girlfriend was hot like me?", and Johnny Awesome being mistaken for a girl and called "Jenny" by a character in Hillsbrad.
Male night elves are somewhat more masculine, but even they will occasionally do a somersault when they jump.
To be fair, though, they are only effeminate in comparison to the other males in the game, especially when compared to their allies the Horde. And they were even more so in the beta for Burning Crusade.
Bisexual elf Zevran from Dragon Age: Origins mentions this as the reason he and other elves were chosen as assassins. Most humans found them pleasing to look at, which increased the chances they'd be successful in their jobs. Zevran himself is a prime example of this trope at work - drunken dwarf Oghren even comments that Zevran's got "small breasts for a gal".
Similarly, Fenris of Dragon Age II. He's more masculine than some examples, but between the lean elven body model and pretty face, he hits the Pretty Boy mark. It's even lampshaded by Hawke's uncle Gamlen if a male Hawke romances Fenris.
"So, you're into elves, huh? I guess I don't have to ask which one of you's the girl."
Lieutenant Yaha of Drakengard 2 is a Camp GayDepraved Homosexual who is obsessed with party member Urick to the point that he gave up his ability to feel pleasure for the ability of charm. He spends his boss battle making creepy remarks towards both Urick and Nowe.
More-or-less averted in Rift: Although smooth-faced and clearly intended to be attractive (even if Kelari are a bit eerie-looking), elven men are too sinewy and rawboned to be called Pretty Boys.
Mostly averted in Dwarf Fortress by virtue of elves being nothing but a lowercase 'e' on the screen. However, their leadership positions are titled "queen" and "princess"... even when the elves in those positions are male.
Worth mentioning is that the Ambiguous Gender of Vaarsuvius (one of the aforementioned parents) has been a running joke for a long time (even if it wasn't meant to be ambiguous at first). Also, the children are adopted, so any of the four gender combinations for two people is possible for V and his/her spouse.
Subverted later when Justin admits he likes his men manly.
In DM of the Rings, Aragorn in particular seems to look at any Elf and think it's a woman, even when they're male. For the most part however he just plays it up to annoy Legolas' (AKA Leggo Lass) player.
Even invoked when he's trying to get laid with Éowyn, but the DM doesn't want to because he's having to play her:
Éowyn: This [Aragorn hitting on the DM as her] is just too weird. Aragorn: Oh, come on, you said she was hot! "Tall, slim, and graceful, with golden hair", you said. Éowyn: That's the same description I gave you for Legolas. Aragorn: Like I said: hot!
Used to point up the gender stereotypes in Yet Another Fantasy Gamer Comic: male high elves (who come from a gender-equal race) are swishy, while male drow (who come from a matriachal society) are masculine. However, male high elves are still manly enough to be jealous as all hell of a drow who "slept [his] way to this position".
Averted in Dubious Company, the sex of the elves in the series are easily distinguishable, except for Elly. He is mistaken as a girl at least once by everyone, and consistently by Marty. Tiren cursing him didn't help matters either.
Done very specifically with Cale, but, in an aversion, not with elves as a whole. Note, that this is barely apparent to the readers, if at all.
Elon and Rolan of Ears for Elves are both somewhat femenine, in particular in hairstyle. The former has girlish bangs and ponytail, whilst Rolan has narrow braids in his long hair and multiple earrings. Tanna (actually female) also queries whether someone calling "princess" is referring to Elon, much to his annoyance.
Fredrik K.T. Andersson (the author of Pawn) has a mostly-NSFW series of drawings about adventures of "the bard who knocks up every critter in creation" (though evidently was too drunk at the time to remember half of those... encounters). Elves were the only beings with whom he had some problems.
Tales of MU subverts this in the case of half-elf Steff, who is genderqueer and dresses as a female. To humans and most other non-elves, she comes off as beautiful and feminine. To elves, she looks awkwardly masculine, like a bad drag queen.