middlesex by jeffrey eugenides. it's fiction but such an awesome book. one of my favs...also, don't be fooled by the oprah's book club recc. i hate chick lit and this book is such a winner. so well-written and such an interesting story.
graphic novels: if you like history, i'd suggest maus by art spiegalman (the complete was just released, it was previously maus I and II)
y: the last man by bryan k. vaughan. this 50 issue comic just wrapped up earlier this year and is one of the best fucking stories i've read in a looooong time. seriously. every male creature on the face of the earth has been killed save yorick and his pet monkey ampersand...he's trying to get to the girlfriend who was studying in austrailia at the time of the 'plague' and at the same time is the last hope for humanity. lots of awesomeness ensues.
the scott pilgrim series by bryan lee o'malley. its funny, easy to read and a lot of fun, especially if you''re in your mid to late 20s. lots and lots of pop culture refs - you know, if you're into that sort of thing.
neil gaiman's sandman series is also worth a read. good times, graphic shit and well-written myths.
and finally, if i need to tell you to read watchmen...it would come accompanied by a smack to the back of the head.