I've got many series on the go. Some of my favourites:
House of Night
Okay, I actually dislike this series. I only keep reading it for the love triangles, and 'cause all my friends love it and we need something to talk about. Fourth book totally annoyed me, though. The only part of it I can even remember is that Aphrodite got a cat. Uhhhm.
The Mortal Intruments
Again, I don't actually like the series... It just amuses me. The characters are lovable, but stupid. <3 Jace, Clary, you're not related. Figure it out, please.
Uglies/Pretties/Specials
Actually finished this series a while ago; gotta say, I loved it. Heart heart heart. Read it. Read it now.
The Gemma Doyle Trilogy
Only read the first one. I found it... slow, I guess? I'd recommend it, though. I enjoyed it--it just wasn't life-changing. I agree; I fail to see why it's so popular.
Wicked Lovely
Loved it. <3 Melissa Marr really pulls off the whole fairy thing, I think. Just stay away from Ink Exchange.
Vampire Academy
Yet another vampire highschool romance--so shoot me? I like it way more than House of Night, though it took me a while to get over the cover art. Seriously, nobody's boobs have to be that big, Rose. Anyways, I'll admit it--I'm hooked. Dimitri stole my heart.
I also recently finished reading Evernight, Need, and various other fantasies that I sort of liked, sort of didn't. And some other this-world teenage dramas. Yay for vague. As of this moment, I'm between books. I may give Shadowmancer another go, perhaps?
Oh, and I once heard Jodi Picoult described as YA. Don't know if she counts, but if she does, her books definitely deserve to be on the read list. <3