Series are wonderful! It's like a story that doesn't end...until it does. But at least it's lengthened out. The only bummer is waiting for the next book it's not all published.
Here's some series I've read and loved...or read and loved and then didn't.
Artemis Fowl
By Eoin Colfer
April 2001
Hardcover, 277 pages
8 books in the series
"This rip-roaring, 21st-century romp of the highest order is a combination of folklore, fantasy, and a fistful of high-tech. These two crime caper fantasies feature anti-hero Artemis Fowl, a twelve-year-old boy-genius and the last of a clan of international underworld figures and con artists. Rough 'n' tumble storytelling with plenty of attitude.
From a strikingly original new voice comes the story of Artemis Fowl, a very unusual hero. Artemis is a genius, a criminal mastermind, and a millionaire...and he is only twelve years old! A combination of Sherlock Holmes, James Bond, and Attila the Hun, even Artemis doesn't know what he's taken on when he kidnaps a fairy — because these fairies are armed and dangerous, and don't play by any rules!"
I love this series....except for # 7. Can you have a favorite series and not finish one of the books? Ahh! And since I haven't read #8, the last one, that came out July 2012 I can't tell about that one. So, at least the first 6 books are great. So...I'd still suggest reading this one. Criminal mastermind 12 year old. It's just fun!
Recommended for ages 11-14.
By the way, his book signings/shows are entertaining. Though as he's gotten BIG, it seems that there's not that "quality" time with the readers as they're passing through the conveyor belt. I believe I'd asked him about adding a book to his Supernaturalist one, which he said he would. But we're still waiting for that.
Gregor the Overlander
By Suzanne Collins
Scholastic, 2003
Paperback, 310 pages
5 books in the series
When Gregor falls through a grate in the laundry room of his apartment building, he hurtles into the dark Underland, where spiders, rats, cockroaches coexist uneasily with humans. This world is on the brink of war, and Gregor's arrival is no accident. A prophecy foretells that Gregor has a role to play in the Underland's uncertain future. Gregor wants no part of it until he realizes it's the only way to solve the mystery of his father's disappearance. Reluctantly, Gregor embarks on a dangerous adventure that will change both him and the Underland forever.
Usually I'm not so into book that have animals in them, but Suzanne Collins (you know, the author of The Hunger Games, in which I'd suggest that it would be a great read....for older kids. Of the mature age. There is a lot of violence. I might just say that would go in the "young adult" category, perfect for zombiemommies.net)
Anyway- I read this one long ago, after I had read the first book in the Hunger Games trilogy and it was nice to know that Suzanne Collins knows how to write entertaining books.
I've been to one of her book signings as well. And I was able to get a picture with her.
Recommended ages 11-14.
Mercy Watson to the Rescue
By Kate DiCamillo, Illustrated by Chris Van Dusen
Candlewick Press, August 2005
Hardcover, 80 pages
5 books in the series
"Have Mercy! Get ready for an exciting new series from Newbery Medal winner Kate DiCamillo
To Mr. and Mrs. Watson, Mercy is not just a pig -- she's a porcine wonder. And to the portly and good-natured Mercy, the Watsons are an excellent source of buttered toast, not to mention that buttery-toasty feeling she gets when she snuggles into bed with them. This is not, however, so good for the Watsons' bed. BOOM! CRACK! As the bed and its occupants slowly sink through the floor, Mercy escapes in a flash -- "to alert the fire department," her owners assure themselves. But could Mercy possibly have another emergency in mind -- like a sudden craving for their neighbors' sugar cookies? Welcome to the wry and endearing world of Mercy Watson -- an ebullient new character for early chapter-book readers in a series that's destined to be a classic.
From the one and only Kate DiCamillo comes an irresistible new hero for early chapter book readers, brightly captured with comic nostalgic flair by Chris Van Dusen."
This is a larger sized book...about 7 x 8 inches. It's colorful and has larger type letters with many pictures. It's great for children transitioning from picture books to chapter books. It is a book with an animal as the main character and is silly! Recommended ages 5-7. The pictures are great inside. The cover doesn't do it enough justice.
By Margaret Peterson Haddix
Simon & Schuster Books for Young Readers, Sept 2008
Hardcover, 160 pages
7 books in the series
"Luke has never been to school. He's never had a birthday party, or gone to a friend's house for an overnight. In fact, Luke has never had a friend.
Luke is one of the shadow children, a third child forbidden by the Population Police. He's lived his entire life in hiding, and now, with a new housing development replacing the woods next to his family's farm, he is no longer even allowed to go outside.
Then, one day Luke sees a girl's face in the window of a house where he knows two other children already live. Finally, he's met a shadow child like himself. Jen is willing to risk everything to come out of the shadows -- does Luke dare to become involved in her dangerous plan? Can he afford not to?"
I'm a fan of Margaret Peterson Haddix. Her stories are creative and mysterious...well some...not all. This is series seems like a popular one among kids ages 8 and up.
If you like fairytales, you should check out Just Ella by Haddix for ages 11-14. It's not a series, but could have been the first book I read of Haddix's. A retelling of Cinderella, but not exactly as you'd think.
Well if you like series, there's a few to entertain! What are some series you like?
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, which has it for $1 cheaper. Even the husband seems to like it. He's making his own words to the music. 
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by Jon Scieszka--it is awesome and funny!) The illustrations of Infinity and Me were fantastic- if you like that kind of illustration. It's beautiful, but not my personal preference.