From my own shelf:
The Girl with the Dragon Tattoo
The Girl on the Train
The Good Girl
The House Girl
Luckiest Girl Alive
Goodreads has a list of almost 800. And a lot of them deal with actual grown women and not girls.
Emily St. John-Mandel looked into this, in a piece titled "This Is Why So Many Books Have 'Girl' In The Title" by Lena Grossman. St. John-Mandel actually put together a list with over 800 titles (eliminated children's books, and books with less than 250 ratings) and found that more than half of the titles dealt with "girls" that were in fact women.
Having "girl" in the title doesn't make a book bad. It doesn't really say much about the book. Really, it says more about the marketing. An NPR story says it's not just about marketing, though the interview seems to suggest that yeah, it is about marketing. Gone Girl and The Girl on the Train did well so "girl" in the title becomes sort of a shorthand, telling you if you liked X then you'll definitely like Y. Though of course it's not to say no books had "girl" in the title before Gone Girl. Three of the books I listed at the top of this post were published pre-Gone Girl.
The point is, this is a trend I'm not crazy about. When there's a few, it didn't bother me. I didn't think twice about it. Then I started noticing it everywhere. Obviously I'm not the only one (hence those links above). This is like the "Wife" trend (as was pointed out by others as well, so well-trod ground here), where it seemed that ever other book was the "something-something Wife". And just like with the "girls" trend, the title doesn't necessarily reflect on the quality of the book, nor does a few instances mean much. But once you start seeing it over and over, it started to leave a bad taste in my mouth.
I'm not crazy about the infantilization of women being referred to as "girls". I'm not crazy about the stories about women being framed in their relation to a man.