Generation Dead - Daniel Waters (The sequel is out now. It’s called Kiss of Life)
If you liked Twilight, I would recommend this one. It was a really good book, but it didn't rip off the vampire idea. It is definitely worth reading.
~~A quick summary~~
All over the country, something strange is happening. Teenagers who die aren't staying dead. They are coming back to life, but they come back different - they stutter and their reactions to everything are slower. Termed 'living impaired' or 'differently biotic', there are lots of conspiracy theories to explain this new phenomenon. But as their numbers keep on growing, so does the discomfort of the living people in the community. When Phoebe falls for Tommy Williams, one of the ‘living impaired’ boys, her best friend and star of the football team, Adam, has conflicting emotions. There aren't any laws to protect the 'living impaired' so there's nothing to stop the people who want to get rid of them for good.