Generation Dead (book 1) by Daniel Waters

Kids all over America are dying and coming back....as zombies or living impaired.  Phoebe and Adam are best friends. He loves her but she doesn't know it. She starts hanging out with Tommy, a dead kid. This causes uproar in their town of Oakvale, where the dead kids are not wanted and are treated badly. No one knows why they come back and how come each dead kid is so different.

It was an interesting concept, but for me it just fell flat. I'll read the next one because I want to see what happens with Phoebe and Adam.