If you haven't already read it, and you probably have, Nineteen Eighty-Four is another one of those "has to be read" books. It's not really 'sci-fi' as such, but it is dystopian, and a fantastic piece of literature imo.
I also recently enjoyed reading The Player of Games by Iain Banks. It's sci-fi, but focuses more on the cultural aspects of that than the technology and such. It's about, as you may have guessed, games - not video games, I mean games in a more traditional sense - and touches on how games and the way we play them reflect on us and our society. Worth a read.