Well it looks like I've read a reasonable number of these (highlighted in bold).
1984, George OrwellThe Alchemist, Paulo Coelho
Alice's Adventures In Wonderland, Lewis CarrollAnimal Farm, George OrwellAnna Karenina, Leo Tolstoy
Anne Of Green Gables, L.M. Montgomery
Artemis Fowl, Eoin Colfer
The B.F.G., Roald DahlBirdsong, Sebastian Faulks
Black Beauty, Anna SewellBleak House, Charles Dickens
Brave New World, Aldous Huxley
Brideshead Revisited, Evelyn Waugh
Bridget Jones's Diary, Helen Fielding
Captain Corelli's Mandolin, Louis De Bernieres
Catch 22, Joseph Heller
The Catcher In The Rye, J.D. Salinger
Charlie & The Chocolate Factory, Roald DahlA Christmas Carol, Charles DickensThe Clan Of The Cave Bear, Jean M. Auel
Cold Comfort Farm, Stella Gibbons
The Colour Of Magic, Terry PratchettThe Count Of Monte Cristo, Alexandre DumasCrime And Punishment, Fyodor Dostoyevsky
David Copperfield, Charles Dickens
Double Act, Jacqueline Wilson
Dune, Frank HerbertEmma, Jane Austen
Far From The Madding Crowd, Thomas Hardy
Girls In Love, Jacqueline Wilson
The God Of Small Things, Arundhati Roy
The Godfather, Mario Puzo
Gone With The Wind, Margaret Mitchell
Good Omens, Terry Pratchett & Neil Gaiman.Goodnight Mister Tom, Michelle Magorian
Gormenghast, Mervyn PeakeThe Grapes Of Wrath, John Steinbeck
Great Expectations, Charles DickensThe Great Gatsby, F. Scott Fitzgerald.
Guards! Guards!, Terry PratchettHarry Potter And The Chamber Of Secrets, J. K. Rowling
Harry Potter And The Goblet Of Fire, J. K. Rowling
Harry Potter And The Philosopher's Stone, J. K. Rowling
Harry Potter And The Prisoner Of Azkaban, J. K. Rowling
His Dark Materials Trilogy, Philip Pullman
The Hitchhiker's Guide To The Galaxy, Douglas AdamsThe Hobbit, J. R. R. TolkienHoles, Louis Sachar
I Capture The Castle, Dodie Smith
Jane Eyre, Charlotte Bronte
Kane And Abel, Jeffrey Archer
Katherine, Anya Seton
The Lion, The Witch And The Wardrobe, Cs LewisLittle Women, Louisa May Alcott
Lord Of The Flies, William Golding
The Lord Of The Rings, Jrr TolkienLove In The Time Of Cholera, Gabriel Garcia Marquez
The Magic Faraway Tree, Enid BlytonMagician, Raymond E. FeistThe Magus, John Fowles
Matilda, Roald Dahl
Memoirs Of A Geisha, Arthur Golden
Middlemarch, George Eliot
Midnight's Children, Salman Rushdie
Mort, Terry PratchettNight Watch, Terry PratchettNoughts And Crosses, Malorie Blackman
Of Mice And Men, John Steinbeck
On The Road, Jack Kerouac
One Hundred Years Of Solitude, Gabriel Garcia Marquez
Perfume, Patrick Suskind
Persuasion, Jane Austen
The Pillars Of The Earth, Ken Follett
A Prayer For Owen Meany, John Irving
Pride And Prejudice, Jane Austen
The Princess Diaries, Meg Cabot
The Ragged Trousered Philanthropists, Robert Tressell
Rebecca, Daphne Du Maurier
The Secret Garden, Frances Hodgson BurnettThe Secret History, Donna Tartt
The Shell Seekers, Rosamunde Pilcher
The Stand, Stephen King
The Story Of Tracy Beaker, Jacqueline Wilson
A Suitable Boy, Vikram Seth
Swallows And Amazons, Arthur RansomeA Tale Of Two Cities, Charles Dickens
Tess Of The D'urbervilles, Thomas Hardy
The Thorn Birds, Colleen Mccollough
To Kill A Mockingbird, Harper Lee
A Town Like Alice, Nevil ShuteTreasure Island, Robert Louis StevensonThe Twits, Roald Dahl
Ulysses, James Joyce
Vicky Angel, Jacqueline Wilson
War And Peace, Leo Tolstoy
Watership Down, Richard Adams
The Wind In The Willows, Kenneth GrahameWinnie-The-Pooh, A.A. MilneThe Woman In White, Wilkie Collins
Wuthering Heights, Emily BronteAs you can see, my tastes tend towards the fantasy and science fiction/speculative fiction. I've felt for a while that I've been lacking in the classics department especially living within half an hour of the Bronte Parsonage and I really ought to do some more reading. I was taught to read at a very young age, plied with all the childrens' classics and it shows.
I don't think Pratchett's best books are listed. I can't disagree with Guards Guards but Small Gods is nowhere to be seen. I believe it's one of the best comments on faith verses religion there is.
The problem with these kinds of polls is that they end up being a list of the most popular rather than necessarily the best. For example I love
Storm Constantine's Wraethu books. The problem is that Storm's books are dark and published by a smallish publisher without the clout of the larger ones. So she has a small but dedicated band of readers and will never score or these kinds of polls.