The Bible deserves to be on any list, even though the vast majority of it is horrible dull reading. It's is the most influential book of history.
I wonder why Inferno got to be there, even though it's just part of Divine Comedy (mind you, Inferno is the most important part).
L'Morte De Arthur is also important becuase it's the focal point for all Arthurian legends, which are pretty big by themselves.
I wonder why Canterbury Tales isn't on there? Or any of King's works. Or Ender's Game. Online polls are not definitive, mind you, asking literary critic's will get lots of pompous crap.
I have to argue with you on some points Piecewise.
Lord of the Rings is the Ur Example of High Fantasy, DF is a derivative of this genre, claiming that DF is enough LotR, is kinda silly.
Harry Potter: Despite the fact that they follow a similar structure, the books have greatly different plot. And the last book changes the structure anyway.
TKaM is a beautiful book. And I don't say that lightly. Aticus alone makes this book worth it by his awesomeness.
The Bible. Bronze age superstitions? Really? It still forms an important part of thinking for, you know, most of the world (and I'd guess that you'd say the same thing about any other religious document, which is kinda sad)
Shakespeare. Zeroth Law of Tropes, "irregardless of what you're idea is, Shakespeare had a form of it written already." Tough to read, true, but a decent translation helps a lot.
Hobbit: Honestly, I liked it better than the Trilogy. Tighter plot.
Narnia: Allegories can be read more than one way. I enjoy them just fine as a heroic allegory for mankind preserving.
Pooh: One's never too old for the innocence of childhood.
Tale of Two cites: Don't like heroic sacrifices, I take it?