(Not in any particular order.)
1. Eternal love. You know, the kind where for whatever reason, the protagonist (usually a girl) is reincarnated but never remembers the past, and her romantic meant-to-be interest (usually the brooding, semi-abusive guy) is stalking/"educating" her about her past. Plus some nonsensical danger thing. Sometimes involving a curse.
2. Vampires. Way back in the day (as in, WAY before vampires spiked) there were some novels I remember as being pretty cool (as in not totally sucky) -- Robin McKinley's Sunshine, Annette Curtis Klause's The Silver Kiss, and (for some random reason) Amelia Atwater-Rhodes' In the Forests of the Night. I haven't picked these up in a while, but from what I recall, the main difference was that the vampire trope was not just a foil for eternal love and crap like that. There was actually a plot. Shocking, I know.
3. Werewolves. I don't know if I've ever read a really good werewolf novel. I like the way they're dealt with in the earlier Anita Blake books, but those are certainly not YA. (Same with vampires. The early Blake books are kind of awesome.)
4. Fairies. Have I ever read a good fairy book? (I'm talking "the fair folk" sorts of stories, not "fairy tales." The two are very different.) Perhaps the only books I have ever loved that had fairies as a factor were Daughter of the Forest, by Juliet Marillier, and sequels. Probably because again, the fairies were not the love interests. Although technically, that book is both a "fair folk" and a "fairy tale" book.
5. Angels. You know it's awful when you've only read ONE book featuring angels, and the thought of more makes you gag.
It's not that I hate vampires, werewolves, or fairies. It's that I detest all books that use these tropes just to carry some half-assed story about forbidden/destined/eternal/teenage love. Period.
Any trends you're sick of? Please share!