I spent a few years as a book employee. There are literally millions of young adult books, most of which are pretty gender neutral. There are a few that happen to appeal more to boys depending on local culture, like Hugo, the Alex Ryder series (by Tom Clancy), Percy Jackson and the Olympians, Cirque du Freak, and a few others. But I had girls who bought these too.
Now a note on school libraries, I've taught seminars in both Wales and America, and I was able to see a bit of the grade school in both areas, only as a student in America though, plus what I've learned since my son started Kindergarden this year:
Different school districts have restrictions on what is deemed acceptable to certain age groups and certain subjects. Especially since budgets are being cut, there isn't the money to restock books the way they would probably like.
For example, the Lord of the Rings Trilogy wasn't available until 8th year for check out. Robert Jordan was banned even in high school due to a few "sex scenes" (the writer said they had sex). More parents over here at least in the South are really restricting what is "safe" for their kids to read. And in our school system, one parent with a big enough mouth is enough to have it banned for the majority.
So more traditionally female enjoyed series like the Saddle Club, Babysitter's Club, and Beverly Clearly's work can get past censors easy. But even a series like Legends of the Guardians can be taken off the shelves. Fear Street, Goosebumps, and whatnot were banned in my school library period.
Which is annoying to say the least because I was the girl bringing my Dad's Stephen King, Dean Koontz, and Tom Clancy to school to read at a young age. I had a teacher confiscate my copy of the Shining
because I was 12 and "shouldn't be reading such filth". I made the office call my father who was on patrol at the time. I still don't know what my dad said to that principal, but all I know is he walked me back to class and told my teacher to never take a book from me again.