I've done displays of:
"Animal Books"- any books about animals or those in which pets play a large role.
"Books to Movies" - it's amazing how many of these there are from which to choose.
"World War II Books" - anything set in that time period, not just 'war' books.
"... Mysteries" - pick a sub-genre to highlight: romantic, sci-fi, fantasy, etc.
"Books of Mythical Proportions" - books that include some sort of Roman or Greek mythological character - ex. Percy Jackson
"Never Bored @ Boarding School" - tons of series to choose from for this one!
"Away to Faerie" - any faerie books
"Fairy Tale Redux" - the "Once Upon A Time" series along with any other retellings of classic stories

I'm just a clerk but I can tell you what a lot of the kids check out. Zombies are still big, why I don't know. Marvel Zombies especially. So is Anime and Manga. Especially fairy tale based ones. I don't actually see a lot of vampire ones. I do see some kids whom are old enough for YA books go back to things like Nancy Drew and the Hardy Boys - the old originals, not the new ones. (I was always most fond of Alfred Hitchcock's Three Investigators, myself.) Also graphic novel versions of classic books do well.

I live for displays!

With The Road coming out in theaters, I'm going to use the next two weeks to do a book/movie display. I have my doubts that teens will be stampeding to check out The Road, but they might like some of the Star Wars books, Sisterhood of the Traveling Pants, Push, Princess Diaries, Narnia series, Princess Bride, etc. If your library lets you you can even display DVD and books side by side (for the ones on DVD)

Thanksgiving is tough for the teen crowd, but I like to do mixed concept displays. Put Native American craft books next to a range of cook books (traditional to vegan) next to the less musty looking pilgrim stuff next to the Chicken Soup books

Right after thanksgiving, I do a display I call "tis the season for giving (and shopping)":

For teens, mostly craft books they can use to make presents, but also our one book on budgeting, and whatever I can pull from the adult section that doesn't look horribly boring about consumer affairs.

In the larger adult display: crafts, novels about shopping, consumer reports, fraud protection and warranty stuff, stories about shopping

Then the second week of Dec you're well primed for traditional holiday displays.

After the new year, I'll pull out my "let it snow" display. Books about and involving snow and the things that live there: Climbing everest, alaska travel guides, snow leopards, penguins, weather books...

Something I've been doing in my middle school library is a "If you like R.L. Stine" display. (I have approximately 75 R.L. Stine books, I think 7 is the most I've had actually in the library at one time since the beginning of the year.) I go around the library and pick out other creepy/horror books. Some of my die-hard R.L. Stine readers have even picked up a book or two by another author! :)

Repost from when I did not have an actual account.

1. Rock and Roll All Night and Read Everyday. I cover the background with rock and roll sheet music then put color pictures of rock bands and singers (all types from Elvis the Beatles and other clssics to new groups like Dropkick Murphies and The Killers). I then scatter concert stubs around (if like me you lost most of yours you can find many scans on google images) and hang up old concert t-shirts. If you have young kids these days they might have smaller rock shirts to hang up. Put out books about rock and roll in general and bands specifically.

2.Comic books is a great one. I use old Sunday comics as the background then "borrow" action figures to make the display 3d. The kids love seeing superman fly or spidey climb the wall.

3.A few years ago the NYT Book Review published a map of Manhattan with various literary addresses marked. These were not where F. Scott Fitzgeral lived but rather the Plaza (where Eloise lived) or the address given for Kreizlers Institute in the Alienist. I posted the map then using sting connected the passage in the book giving the address (blown up) to the actual address. This also works with other maps.

A friend who's a high-school librarian had a Sob-o-Meter display. She made a poster of the Sob-O-Meter Guage complete with red arrow. Next she made three display tissue boxes - one tissue box sized that read "Sniff", the next larger that read "Weep", the third very big that said "Sob". She arranged a variety of tear-jerkers, both fiction and non, between the boxes. It was very popular with teens and adults.

Do you know of the Halo video game series? There has been quite a few books and comics based on said games. Order up a bunch of them, decorate your display with some screenshots from the games (GIS "Halo screenshots" or some variation) and maybe a couple of action figures/toys (they have those inspired by the game as well). Teenage boys will eat this up.

When I couldn't think of anything else, I would do a display based on a color. For Christmas you could do a display featuring books with red or green covers. One time I did one with all blue covers: "Don't be blue. Read a good book!" Or a yellow and orange one for summer: "Sunny Summer Reads!" Cheesy, but effective. I particularly liked to do the color displays just before I leave for vacation. That way if a non-teen services staff person is keeping the display filled for me, they only have to look for a book in the teen section with the right color on the cover.

My mentor during a middle school library internship did a neat display with captivating first-lines. I think hers was just a poster with the line, book title, and author, but you could easily display the actual books next to the first lines.

It may be too late to get it started for this month but November is the month of Nanowrimo, National Novel Writing Month, and so a "youth writing" display might be in order.

I also like displays to highlight my sports books -- "Tackle A Good Book" and I put up Football books, "Shoot for a Good Book" and up go the hockey books -- Of course with these displays I also can put emphasis on my favourite sports teams (Posters, Slogans, Clippings) which often gets a rise out of the students.

A take off on the ALA read is to get prominent people who use your library to pose with their favorite books. Instead of just holding the book have them hold the book open covering their faces. Have the patrons guess who!

Good Book Display: Start off with some you like and encourage teens to take a book and leave a book. Self filling display is a great thing!

My favorite display is "Books You Can Judge By Their Covers" because you can show off all your great covers and put up a wide range of books.

I agree with Paige about the non-fiction as well. Teens like it but when it's hidden between all of your educational non-fiction, they don't always know it's there.

We do a "you saw the movie now read the book" display complete with popcorn boxes. Mini reviews can be 'popping' out of books on book marks the shape of large popped kernels of corn.

Around the time of our annual Heart Break Cafe poetry slam we do a large display of poetry books opened to poems that match the theme of love and loss.

We used to do a display around "I hate, hate, hate this book" but our English faculty got mad because so many were on their required book list. The interesting thing was that girls would stand and argue passionately about the books because for each hater, there was someone who loved the book.

The most successful YA display I've ever done was non-fiction. YALSA's annual Best Books for Young Adults lists always have lots of non-fiction titles. Teens also love books with lists like Guiness Book of World Records and the Ripley's Believe It or Not, or things like the Darwin Awards