Martha Baden

I'd particularly recommend The Haunting of Alaizabel Cray and A Great and Terrible Beauty.

A Nightmare's Dozen: Stories From the Dark illustrated by Michael Hussar edited by Michael Sterns.
Frightening tales from a multitude of authors promise to keep you awake at night.

Cirque Du Freak: A Living Nightmare by Darren Shan.
Two boys who are best friends visit an illegal freak show, where an
encounter with a vampire and a deadly spider forces them to make
life-changing choices.

Elsewhere is so original,I had to really think about what books might be like it. Here are a few
suggestions:

Thief in the House of Memory by Tim Wynne-Jones.
The death of an apparent stranger in the Steeple family's old home
triggers troubling questions for sixteen-year-old Declan as he tries to make sense of his fragmented dreams, random memories, and unexplained coincidences, hoping to learn the truth about the mother who suddenly left when he was ten.

Here are some other books that I hope you will like. Like
Sandry's Book, all of these are stories have magic and friendship in
them.
If you haven't read the three books by Tamora Pierce that come after
Sandry's Book, I'd definitely recommend the rest of the Circle of Magic quartet:
 

The Extraordinary Adventures of Alfred Kropp by Rick Yancey.
Through a series of dangerous and violent misadventures, teenage loser Alfred Kropp rescues King Arthur's legendary sword Excalibur from the forces of evil.

The Mysterious Benedict Society by Trent Lee Stewart.
After passing a series of mind-bending tests, four children are selected for a secret mission that requires them to go undercover at the Learning Institute for the Very Enlightened, where the only rule is that there are no rules.

Brian Jacques is hard to beat for a rousing war-like fantasy, but here
are a few titles that you might want to try. All of these books have
sequels or are part of a series.

Artemis Fowl by Eoin Colfer.

When a twelve-year-old evil genius tries to restore his family fortune
by capturing a fairy and demanding a ransom in gold, the fairies fight
back with magic, technology, and a particularly nasty troll.

Sea of Trolls by Nancy Farmer.

If you haven't read the sequels to Angus, Thongs and Full-Frontal Snogging,
you should give those a try:

On the Bright Side, I'm Now the Girlfriend of a Sex God: Further
Confessions of Georgia Nicholson.
 

Knocked Out by My Nunga-Nungas: Further, Further Confessions of Georgia
Nicolson.
 

Dancing in My Nuddy-Pants: Even Further Confessions of Georgia Nicolson.
 

Away Laughing on a Fast Camel: Even More Confessions of Georgia Nicolson.
 

Here are some other books that have danger, intrigue and some romance (or at
least flirtation!)

H.I.V.E. Higher Institute of Villainous Education by Mark Walden.

Swept away to a hidden academy for training budding evil geniuses, Otto,
a brilliant orphan, Wing, a sensitive warrior, Laura, a shy computer
specialist, and Shelby, an infamous jewel thief, plot to beat the odds
and escape the prison known as H.I.V.E.

Thieves Like Us by Stephen Cole.

If you like the Gossip Girl series, you
might want to try some of these:

Peaches by Jodi Lynn Anderson.

Three teenaged girls from very different backgrounds, thrown together to
pick peaches in a Georgia orchard, spend a summer in pursuit of the
right boy, the truest of friends, and the perfect peach.

Au Pairs: a Novel by Melissa de la Cruz.

If you liked the passion between Edward and Bella in New Moon you might
try one of these. The first three are horror or fantasy, and the last
two are just good love stories!

The Silver Kiss by Annette Curtis Klause.

A mysterious teenage boy harboring a dark secret helps Zoe come to terms
with her mother's terminal illness.

Haunted: A Tale of the Mediator by Meg Cabot.

If you liked the Gregor books, you might
like one of these:

City of Ember by Jeanne Duprau (and sequels).

In the year 241, twelve-year-old Lina trades jobs on Assignment Day to
be a Messenger to run to new places in her decaying but beloved city,
perhaps even to glimpse Unknown Regions.

Island of the Aunts by Eva Ibbotson.