My vote for the back from the grave nightmare supplement would be
The Complete Sages and Specialists, v3.5: an NPC class campaign.
Or, if it's something new, it could be a DM's Guide To 101 Nasty And Permanent Disabilities To Inflict Upon PCs That They Can Only Get Rid Of By Roleplaying And Not By Casting Spells Such As Heal, Greater Restoration, Regenerate, True Resurrection and Miracle.
Reaslistically, though, I think it will be a book on Undead, or maybe Fiends, along the lines of Draconomicon.