NPR did a survey and came up with what they consider the 100 greatest Science Fiction and Fantasy books of all time. "Books" is used loosely, as several short story collections and some graphic novels are included, but I shant quibble about that. Overall, it's an interesting list, though there are definitely some entries that sparked a "WTF!" from me. (Chief among which are 12, 50, 54, 73 and 99. Especially 99!) And 92 just elicited a "who?" Definitely a good set of volumes over many decades though, not too heavy on recent books, which is often a problem with these kinds of lists.
I have read a lot of the first half, much less of the second. That's not surprising, as my reading preferences fall into certainly particular (though wide-ranging) styles.