This has probably been posted before, but I've just seen it on another forum and it's got me thinking.
I don't want to hear about the best books you've read, but the ones that change the way you think.
Mine are:
Cat's Cradle - Kurt Vonnegut (an absolutely ripping satire on politics and the nature of man)
Stark - Ben Elton (the root of my green politics I think)
Ulyses - James Joyce (didn't get very far: made me realise I'm not as clever as i thought I was )
I'm sure there are more though.