The Guardian put out a 100 Must Read books list. I can use it as a guideline at least, though I've read a good chunk of them.

1 Pride and Prejudice Jane Austen (I have it, I keep meaning to read it)
2 The Lord of the Rings JRR Tolkien (I've read through 1/2 the trilogy)
3 Jane Eyre Charlotte Bronte

4 Harry Potter series JK Rowling
5 To Kill a Mockingbird Harper Lee
6 The Bible
7 Wuthering Heights Emily Bronte
8 Nineteen Eighty-Four George Orwell
9 His Dark Materials Philip Pullman
10 Great Expectations Charles Dickens
11 Little Women Louisa M Alcott
12 Tess of the d'Urbervilles Thomas Hardy
13 Catch-22 Joseph Heller
14 Complete Works of Shakespeare William Shakespeare
15 Rebecca Daphne Du Maurier
16 The Hobbit JRR Tolkien

17 Birdsong Sebastian Faulks
18 Catcher in the Rye JD Salinger
19 The Time Traveler's Wife Audrey Niffenegger
20 Middlemarch George Eliot
21 Gone With The Wind Margaret Mitchell
22 The Great Gatsby F Scott Fitzgerald
23 Bleak House Charles Dickens
24 War and Peace Leo Tolstoy
25 The Hitch Hiker's Guide to the Galaxy Douglas Adams
26 Brideshead Revisited Evelyn Waugh
27 Crime and Punishment Fyodor Dostoyevsky
28 Grapes of Wrath John Steinbeck
29 Alice in Wonderland Lewis Carroll
30 The Wind in the Willows Kenneth Grahame
31 Anna Karenina Leo Tolstoy
32 David Copperfield Charles Dickens
33 Chronicles of Narnia CS Lewis
34 Emma Jane Austen
35 Persuasion Jane Austen
36 The Lion, The Witch and The Wardrobe CS Lewis
37 The Kite Runner Khaled Hosseini

38 Captain Corelli's Mandolin Louis de Bernières
39 Memoirs of a Geisha Arthur Golden
40 Winnie the Pooh AA Milne
41 Animal Farm George Orwell
42 The Da Vinci Code Dan Brown
43 One Hundred Years of Solitude Gabriel Garcia Marquez (My first dip into this author is Love in the Time of Cholera, haven't finished it yet)
44 A Prayer for Owen Meaney John Irving
45 The Woman in White Wilkie Collins
46 Anne of Green Gables LM Montgomery
47 Far From The Madding Crowd Thomas Hardy
48 The Handmaid's Tale Margaret Atwood
49 Lord of the Flies William Golding
50 Atonement Ian McEwan
51 Life of Pi Yann Martel (I started this one and just couldn't finish it)
52 Dune Frank Herbert (Bought it recently, read the first page... I'll go back to it sometime)
53 Cold Comfort Farm Stella Gibbons
54 Sense and Sensibility Jane Austen
55 A Suitable Boy Vikram Seth
56 The Shadow of the Wind Carlos Ruiz Zafon
57 A Tale Of Two Cities Charles Dickens
58 Brave New World Aldous Huxley
59 The Curious Incident of the Dog in the Night-time Mark Haddon
60 Love In The Time Of Cholera Gabriel Garcia Marquez (oh yeah.. reading this one now)
61 Of Mice and Men John Steinbeck

62 Lolita Vladimir Nabokov
63 The Secret History Donna Tartt
64 The Lovely Bones Alice Sebold
65 Count of Monte Cristo Alexandre Dumas
66 On The Road Jack Kerouac
67 Jude the Obscure Thomas Hardy
68 Bridget Jones's Diary Helen Fielding
69 Midnight's Children Salman Rushdie
70 Moby Dick Herman Melville
71 Oliver Twist Charles Dickens
72 Dracula Bram Stoker
73 The Secret Garden Frances Hodgson Burnett
74 Notes From A Small Island Bill Bryson
75 Ulysses James Joyce
76 The Bell Jar Sylvia Plath
77 Swallows and Amazons Arthur Ransome
78 Germinal Emile Zola
79 Vanity Fair William Makepeace Thackeray
80 Possession AS Byatt
81 A Christmas Carol Charles Dickens
82 Cloud Atlas David Mitchell
83 The Color Purple Alice Walker (I tried to read this one)
84 The Remains of the Day Kazuo Ishiguro
85 Madame Bovary Gustave Flaubert (Read it in French in High School)
86 A Fine Balance Rohinton Mistry (reading it now)
87 Charlotte's Web EB White
88 The Five People You Meet In Heaven Mitch Alborn
89 Adventures of Sherlock Holmes Sir Arthur Conan Doyle
90 The Faraway Tree Collection Enid Blyton
91 Heart of Darkness Joseph Conrad
92 The Little Prince Antoine de Saint-Exupery

93 The Wasp Factory Iain Banks
94 Watership Down Richard Adams
95 A Confederacy of Dunces John Kennedy Toole
96 A Town Like Alice Nevil Shute
97 The Three Musketeers Alexandre Dumas
98 Hamlet William Shakespeare
99 Charlie and the Chocolate Factory Roald Dahl
100 Les Misérables Victor Hugo (Have had it for years, never sat down to read it)