This is a brilliant idea--Neil Gaiman is awesome for headlining it. (Well, Neil is awesome just because he's Neil.) You probably couldn't get away with handing out books for Halloween instead of candy but...how about starting with friends and family? I think it's time for a new Halloween tradition around my house.
My picks for gifting:
4-8 year old range: The Witch Next Door by Norman Bridwell
7-10 year old range: Mr. Katz is a Zombie by Margaret Lesh
11-15 year old range (and beyond): The Graveyard Book by Neil Gaiman
Adults (and since the shops insist on lumping Halloween and Christmas together): Krampus: The Yule Lord by Brom
I'll offer up my own as well
For adults: Between and Struck by Clarissa Johal