That's a tough one. If I can only list two, I'll go with:
The Good Earth, by Pearl Buck
Being There, by Jerzy Kosinski
I pick the first because it is set in a rural China and stresses the importance of family and the land. I choose the second because, as a satire on the power of the media, it's as relevant today as it was when it was written in 1971. Both books, incidentally, were made into movies too!
Wild at Heart and
The first one helps you find yourself, and the second one teaches you how to cook easy delicious food !!!
Hmm... so many good books to choose from. :)
I guess my favorite is The Name of the Rose by Umberto Eco. I read it countless times and it's the first book i recommend when people ask.