If you can find them, I would suggest the Diadem series by John Peel... I enjoy them very much. I first read them when I was quite a bit younger, but I still enjoy them. They might be a bit hard to find, though... I think there are six books in the series, I think:
#1 Book of Names, #2 Book of Signs, #3 Book of Magic, #4 Book of Thunder, #5 Book of Earth (my personal favorite), and
#6 Book of Nightmares. I suggested these books my brother (when he was 12) and he enjoyed them... he doesn't really like to read.
Hmmm... Midnighters by Scott Westerfel is a great series, a good midnight read and daytime as well. I've only read the first one,
The Secret Hour, so far, but am waiting for the second to become available at the library.
Abarat by Clive Barker is great, both books of them. =) The main character is a girl, however, I doubt it is girly...
The Pendragon Series by D.J. Machale... very interesting. I've only read the first one, but it is definately worth reading.
The Stravaganza series by Mary Hoffman... another great read. Again, I've only read the first (out of three so far), but I'm awaiting the second to become available at the library. The first is the
City of Masks.
Terry Brooks is a great author, all his works are good. I especially like the The Word & the Void Trilogy (
Running with the Demon, A Knight of the Word, and Angel Fire East). Too bad its only a trilogy, I really wanted to see what happened next. The numerous Shannara series are well known, and The Magic Kingdom of Landover are great books as well.
His Dark Materials by Phillip Pullman... awesome series, one of my favorites. Very well done series.
And, of course, the books that have already been suggested.
Out of them:
I have loved all of Eoin Colfer's books that I have read. The Artemis Fowl series was good, but that wasn't the only one.
I enjoyed
The Wishlist very much, also.
Rowan of Rin is the only one I've read out of the Rowan series, but I enjoyed it. I see the others quite often, if I could just figure out the order of them...
Avi I haven't read many works on, and the works I remember I don't know if are considered too girly or not. I did enjoy them, however.
I think I have everything... I could probably recommend a lot more to you, but they skip my mind at the moment. I usually don't suggest them unless I think they are worth suggesting, so...