I really suggest Lois Lowry, especially Number the Stars and The Giver.  I also enjoyed Arthur Conan Doyle when I was young.  My students definitely enjoy some of the classics, but they also really are into dystopia, or stories where everything is really going wrong.

Though I do not tend to enjoy them personally, I have to agree with post #3 that series books are an easy route to increasing your to-read list quickly.  Find a series (or simply an author) that you enjoy and read all of the publications within.  In that vein, Jodi Piccoult is an author that many young-adult female readers enjoy.  She has a very definite style, but her books tend to run the gammut of social and emotional themes.

For pleasure reading, I tend to encourage students to avoid the classics (personally) because they are so much easier to enjoy when studied with a class. Most of my 9th grade students loved the Twilight series (not my favorite) and I can personally recommend The Hunger Games trilogy.  

John Green is another modern author who is quickly rising on my to-read list, and he mainly writes for a young adult audience.

Since I see that you are in 9th grade, let me make this recommendation off of what post #2 suggested-- Do not read A Handmaid's Tale.  It is way too mature for a ninth grader and will have you wanting to claw your eyes out from the sheer grossness of some of the scenes.  I read it in college and felt that way, so I can only imagine how disturbing the book could be for a ninth grader. 

Here are some additional suggestions that I have recently added to my reading shelf at school for my students.  All of these books have been published recently: 

The Mortal Instruments series by Cassandra Clare.  The first book is called City of Bones, and all of the books are an exciting combination of romance, fantasy, and humor.  The main character Clary begins to see strange things and then suspects that she may have witnessed a murder at a club one night; the entire series kept me guessing (and reading frantically) until I had finished the last one.

The Beautiful Creatures series by Kami Garcia and Margaret Stohl.  The first book is called Beautiful Creatures and is a dark Southern gothic fantasy, taking place in a small town.  This book has great romance between two unlikely characters, and what I really liked about it was that the romance and the story was told from the perspective of the boy.  There are three novels out right now in the series with a fourth one on the way.  The first book is also going to be made into a movie. 

The Scorpio Races by Maggie Stiefvater.  This novel's dark premise is extremely compelling:  Imagine competing in a horse race in which you not only have to worry about falling off your mount, but the other horses might actually try to eat you.  Stiefvater uses folklore to create an extremely suspenseful story about a young girl who enters her horse (a regular normal horse) in the 'Scorpio Races' to save her family's home, but the races are extremely dangerous because the men compete on these really vicious (but extremely fast) 'water horses.'  The story line sounds a little bizarre, but was gorgeously written, romantic, and suspenseful as all get-out.

You are in luck. There are many, many good and great books out there that fit your interests. For pure pleasure reading, I like to recommend some of the popular fiction writers like Michael Crichton (Jurassic Park; Congo) and Dan Brown (The DaVinci Code). These writers specialize in mystery/suspense fiction. 

For more literary material suitable for yound adults, these books are worth looking into: 

• The Catcher in the Rye
• A Handmaid's Tale
• Pride and Prejudice