Any Dr. Seuss book
Lloyd Alexander’s Prydain Chronicles
Anne McCaffrey’s Pern books
Piers Anthony’s Xanth series
zillions of comic books
zillions of comic strip collections (Peanuts, BC, Wizard of Id, Garfield)
The Choose Your Own Adventure books
The D&D versions of those
The Be an Interplanetary Spy series of the same ilk
zillions of books about outer space (Our Universe was the most-read)
The Thorton W. Burgess books were probably my favorites as a small child. Old Mr. Toad, Jimmy Skunk, Prickly Porky the Porcupine, Lightfoot the Deer, etc. My grandmother read them to me all the time.
Another favorite was Dr. Goat: “Doctor Goat put on his coat and went out to make some calls. He went to the house of a mouse with mumps, he cured a frog who had the jumps, busy old Dr. Goat.”
The Girl With The Silver Eyes is my hands-down favorite. I recently bought a copy for my niece. It’s probably the only children’s book I still own.
It doesn’t look like they’ve been mentioned yet, so I’ll add Blueberries for Sal and Harold and the Purple Crayon.
I can’t think of the author/illustrator, but one of the characters was Loley(sp?) Worm. Anyone know what I’m remembering?
It’s Lowly Worm, and the author is Richard Scarry.
I loved Harold and the Purple Crayon.
Incomplete list:
any Dr Seuss
a James Thurber book about dresses, can’t remember title (kid’s book)
Little House series
Ramona and all her friends–Clearly was so good. (not dead, but not writing)
Snow Treasure–a Weekly Reader book I read to pieces. I still want to go to Norway, based on this book.
The Forgotten Door–another WR item.
Roald Dahl books
Nancy Drew and Cherry Ames (I read my mother’s)
Encyclopedia Brown series
Frances Hodgson Burnett books, but most particularly Secret Garden and Little Princess
The Wolves of Willoughby Chase
From the Mixed Up Files of Mrs Basil E Frankweiler
Black Beauty
Big Red series
The Phantom Tollbooth
The Borrower’s series
Harriet the Spy
The Rats of NIMH
Up a Road Slowly
Anne of Green Gables books
Island of the Blue Dolphins
Julie and the Wolves etc
And many many more…
I loved this book as a kid, and it’s one of my favorites to read to my girls, so when my daughter read it to me last week, there were tears of pride in my eyes.
Now I gotta find a Lego set suitable for building steam shovels…
Wow, what a list!
(I read most of them when I could.)
When I was a very small child my mother read all the Raggedy Ann and Raggedy Andy stories to me. I still get nostalgic over dolls with shoe-button eyes.
When I was a little older I got The Wind in the Willows, which I still read at least once a year. Guess it had an effect on me; I have a stuffed Toad from the original illustrations sitting on my bookshelves with my medical reference books and I’ve read the sequels too. You got to love a title like Toad Triumphant. (Though I loved Water Rat and Mole, those sweet souls.)
And I devoured the Nancy Drew books . . . and while these are not children’s books per se, when I was small I ran through all the Edgar Rice Burroughs Tarzan books and then went on to Jules Verne . . . and science fiction . . . and started in on Rex Stout’s Nero Wolfe mysteries. . . . oh hell, I’ve never stopped reading since.
How could I forget Raggedy Anne and Andy or WITW?
Also, The Tale of the Land of Green Ginger
I read a lot of the Scholastic reading books–the ones you could buy at the book sales in elementary school, too. And who can forget The Weekly Reader? Good times…
While I like many mentioned above, no one remembers poor Danny Dunn 
Even many libraries have withdrawn this series. “Danny Dunn and the Homework Machine” is the most memorable in the series.
I like “Alexander and Terrible, Horrible, No-Good Day”, too. It has appeal to all ages. Read it after a bad day at the office. For kids, it shows we all have days like that, sometimes.
Also:
“Tales of a Fourth Grade Nothing”
“How To Eat Fried Worms”
“From the Mixed-Up Files of Mrs…” I forget, but any librarian would know. It’s classic!
And, for the younger crowd:
“Goodnight Moon”
“Fox in Socks”
“Caps for Sale”
“Ping” (…a chinese story of a tardy duck!)
Tuck Everlasting
Gone Away Lake and its sequel
Charlotte’s Web
anything Beverly Cleary
ditto Judy Blume
the Anastasia series(was that Lois Lowry?)
When I was in maybe second grade, the children’s librarian came in to our class to read excerpts from a few books in an effort to get us interested in the library and reading, and one of those books was called “Stonewords”. It’s about a little girl and her “imaginary” friend, who is really a ghost who needs her help. I must have checked that book out of the library 2 dozen times.
Oh this is fun!
[ul][li]The Winnie the Pooh books, plus Now We Are Six and other poetry by A.A. Milne[/li][li]The Trumpet of the Swan and Charlotte’s Web, by E.B. White[/li][li]The Hundred and One Dalmatians, by Dodie Smith (so much better than the movies!)[/li][li]Little Witch, by Anna Elizabeth Bennett. A Cinderella-like story that’s very bittersweet [/li][li]The Little House series (all except Farmer Boy, which I’ve never read for some reason; probably because it starred an icky boy![/li][li]Danny Dunn and the Homework Machine was a favorite of mine too! I even had the recording of the musical, which I can still sing[/li][li]Twenty and Ten, aka The Secret Cave, by Claire Huchet Bishop[/li][li]Follow My Leader, by an author I don’t remember, alas[/li][li]Cheaper by the Dozen and Belles on Their Toes, by Frank Gilbreth, Jr., and Elizabeth Gilbreth Carey[/li][li]Are You There, God?.. and Then Again, Maybe I Won’t by Judy Blue of course[/li][li]Any Dr. Seuss, but especially Bartholemew and the Oobleck and Horton Hatches the Egg [/li][li]Little Women, the two-part version (ours was separated into two different editions: Little Women and Good Wives. My mom had a bookstore specializing in used and first editions, so my sisters and I were able to read some wonderfully old editions!)[/li][li]From the Mixed-Up Files of Mrs. Basil E. Frankweiler, by E. L. Konigsburg[/li][li]Ginnie and Geneva and Ginnie and the New Girl by Catherine Woolley [/li][li]The World Book Encyclopedia, 1963 edition. A hand-me-down from my older siblings, and pathetically out of date by the time I read it, but gosh, I spent soooo many hours devouring that thing![/li][li]The Second Golden Almanac, a compilation of stories, nature tips, and holiday info published by Golden Books and illustrated by a very young Richard Scarry. Another inheritence from my oldest sister, who’s about ten years older than I am. Actually, I loved most of the Golden Book series and the Big Little Books, too.[/li][li]Caps for Sale, by Esphyr Slobodkina. Anyone else remember this? Gorgeous illustrations.[/li][li]Just So Stories, by Rudyard Kipling. This was an abridged version, but I loved it sooo much, especially because the pictures were amazingly detailed and lifelike[/li][li]Hans Christian Andersen and Grimm Fairy Tales, natch.[/li][li]Bread and Jam for Francis and A Bargain for Francis, by Russell Hoban and Lillian Hoban. (What was Francis, anyway? A badger?) [/li][li]Bambi’s Children, another illustrated and abridged book that made me wish I could draw better [/li][li]Harriet the Spy, who was more like me than I wanted to admit[/li][li]The Lion, the Witch and the Wardrobe*, which was the only Narnia book I read as a youngster.[/li][li]Sarah and Katie, by Dori White, which no one ever remembers. It’s about two friends during the Depression who face a rivalry when a little lying manipulative rich girl moves in[/ul][/li]
Man, I could go on and on, but these are the ones that leapt first to my mind. I still read through many of them now and again. They’re treasures, every one.
I had forgotten Miss Pickerell, and I was trying to remember Mike Mulligan and His Steam Shovel. I think it was the first book I ever took out of the library.
Also:
Ellen Tebbitts. I think I identified with her a little.
There was a book that I read and loved, but I cannot for the life of me remember the title, and apparently I’m the only person who ever read it. It was about a girl named Minx, who lived with a woman who turned out to be a witch. Minx discovered that her real mother was a fairy and her own real name was Minikin(sp.)
I read all the Black Stallion books I could find in the school library.
ETA: *And to Think That I Saw It On Mulberry Street. *
That’s Little Witch, which is on my list too! 
Probably The Lorax
My dad also had a copy of Grimm’s Household Tales. The one in which Cinderella’s step sisters cut off parts of their feet in order to fit in the shoe? In other words not the kiddied up version. I really enjoyed those stories.
That’s really about it. We also had Noddy books and The Berenstain Bears books but I didn’t like those as much as the above.
drm’s post about Cinderella reminds me that I really really should’ve remembered to add The Glass Slipper, the quirky novel take on Cinderella by Eleanor Farjeon, together with The Kings and Queens of England, Farjeon’s book of humorous songs teaching about everyone from William the Conqueror to George VI (and only a line or two about Elizabeth II). Both books were absolutely integral to my childhood, I can’t believe I didn’t include 'em!
Two that haunt me over the years:
Time of Wonder, Robert McCloskey
Ann Can Fly, Fred Phleger
My favorite was probably The Enormous Egg. A farm kid has a chicken that lays this big-ass egg, and it ends up being a triceratops. What kid wouldn’t want to have a pet triceratops?
I also loved Runaway Ralph. Heck, anything by Beverly Cleary was gold.
Loved the **Narnia ** series. Most of it, anyway.
Even though I don’t like dogs, I really got into Where the Red Fern Grows. A really good story, that one.
The only favorites of mine I don’t yet see represented (unless I missed them) are the Betsy-Tacy books by Maud Hart Lovelace and the Great Brain books by John Fitzgerald.
Ok.
The Narnier books
Under the Mountain
The Pern books - not sure if I was under 12 then.
Beatrix Potter stuff
Dr Seuss
Herman the Great
The Biggles books
Many more that I can’t remember.