In succession to this post which seems to have originated a meme, herewith two lists of novels – one list influential when younger, and the other later, with influence measured by strength of memory.  In each case, I include a couple of works of non-fiction, because of their superb writing.
The rules only allow listing of one book per author.   In fact, all the books of some writers would merit inclusion.  In this group, I would include Brautigan, Camus, Conrad, Faulkner, Gordimer, Ishiguro, H. James, Joyce, Maugham, Perec and Turgenev.
Influential when younger:

• Albert Camus:  The Plague
• JM Coetzee:  Waiting for the Barbarians
• Joseph Conrad:  The Secret Agent
• William Faulkner:  As I Lay Dying
• Nadine Gordimer:  Burger’s Daughter
• Joseph Heller:  Catch-22
• Ruth Prawer Jhabvala:  Heat and Dust
• James Joyce:  Ulysses
• Franz Kafka:  The Trial
• Arthur Koestler:  Darkness at Noon
• William Least Heat-Moon:  Blue Highways:  A Journey into America
• Doris Lessing:  The Diary of a Good Neighbour
• Thomas Mann:  Dr Faustus
• Gabriel Garcia Marquez:  100 Years of Solitude
• W. Somerset Maugham:  The Razor’s Edge
• Herman Melville:  Moby Dick
• Gerald Murnane:  Landscape with Landscape
• Michael Ondaatje:  Coming Through Slaughter
• Bertrand Russell:  The Autobiography
• Jean-Paul Sartre:  Nausea
• Mikhail Sholokhov:  And Quiet Flows the Don
• Alice Walker:  The Color Purple
• Patrick White:  Voss
• Yevgeny Zamyatin:  We

Influential more recently:

• Henry Adams:  The Education of Henry Adams
• Richard Brautigan:  An Unfortunate Women:  A Journey
• William Burroughs:  Naked Lunch
• Italo Calvino:  If on a Winter’s Night a Traveller
• Robert Dessaix:  Corfu
• Shusaku Endo: Silence
• Mark Henshaw:  Out of the Line of Fire
• Kazuo Ishiguro:  An Artist of the Floating World
• Henry James:  The Princess Casamassima
• Ryszard Kapuscinski: The Emperor:  Downfall of an Autocrat
• Naguib Mahfouz:  The Journey of Ibn Fattouma
• Norman Mailer:  Harlot’s Ghost
• Alberto Moravia:  Boredom
• Georges Perec:  Things:  A Story of the Sixties
• Antonio Tabucchi:  Pereira Maintains
• Henry David Thoreau:  Cape Cod
• Ivan Turgenev:  Fathers and Sons
• Glenway Wescott:  The Pilgrim Hawk

As these lists may indicate, there are some writers (eg, James, Turgenev) whom one may only appreciate after a certain age and passage of years.
On the other hand, for various different reasons, books by the following authors do not speak at all to me.

• The family Amis
• Saul Bellow
• The family Bronte
• Peter Carey
• David Caute
• George Eliot
• Richard Ford
• Graham Greene
• Ernest Hemingway
• Howard Jacobson
• Thomas Keneally
• Milan Kundera (the Benny Hill of Czech literature)
• Iris Murdoch
• Anthony Powell
• Marcel Proust
• Philip Roth
• Tom Sharpe
• Anthony Trollope
• PG Wodehouse
• and many more.

For some of these authors, the issue may be a generational one:  for example, I know of no members of late Generation Jones or later-born readers who appreciate that early-Baby Boomer obsession, A Dance to the Music of Time, Powell’s long-winded novel sequence.   Added 2013-02-12:    The age threshold of my personal sample is confirmed by that of Max Hastings, writing in 2004:

Anthony Powell’s fan club, always far smaller than that of his contemporary Evelyn Waugh, will continue to shrink as admirers die off and are not replaced.  Nobody whom I know under 40 reads his books, while Waugh’s position as the greatest English novelist of the 20th century seems secure.”

Of course,  not everyone shares my low opinion of Roth’s work.