Sci-fi must-reads?

Well, list some and I'll read away like a constipated god.

P.S.
I read Dan Brown, so feel free to suggest intellectuel books.

>I read Dan Brown, so feel free to suggest intellectual books.

ahahahahah....
Please, his books aren't intellectual. A good read, maybe, but far from intellectual.

Also, Do Androids Dream of Electric Sheep? by Phillip Dick