This one seems like a piece of
cake: the book's called Feed because it's about this
all-pervasive Internet/ social network/ iPod/ video gaming console/ every-smartphone-app-ever-invented
network that most of the people in Anderson's world have installed directly in
their heads.
But the title also suggests some of the other aspects of "feed" and "feeding" that the book totally engages us in. Remember what Violet screams at the other party-goers when she has her meg meltdown at Link's house? Take a quick look: "Look at us! You don't have the feed! You are feed! You're feed! You're being eaten! You're raised for food!" (37.40). No: Violet is not literally referring to anyone being eaten, so don't think that we've now slipped into soylent green mode over here. She's being figurative when she uses "feed" and images of people being devoured.
What she means is that the all-powerful media and its message of constant consumption is removing something vitally human from people. In this sense, the corporations are feeding off of people (both those who have the feed and those who do not). And that's what the title is also asking us to consider.