Artifact book (novel?) that when read teaches you one level of any skill. This may include skills you are restricted in (though it might only raise it to Unskilled) and skills past your role’s cap.

A non-magical book like a novel that describes how to do the invocation.

New type of book “encyclopedia”:

• Appears as a “hardback book” when unidentified, base price 300.
• Nonmagical and always polypiles into a blank spellbook.
• When read, it adds the appearance of some unknown magical items (1d4 if blessed, 1d3 if uncursed, 1 if cursed, plus 1 if you are an Archeologist) to your discovery list.
• It doesn’t disappear when read, but will set a flag that prevents its effects from happening again. This flag will be cleared when creating a bones file.
• Archeologists start with a special blessed encyclopedia (using a different flag), which is their research (the starting one comes pre-read and isn’t useful to this character). Reading an unread archeologist encyclopedia gives the message “These seem to be an archeologist’s notes. You pore over them intently.”, and type-IDs two unknown scrolls, rings, amulets, and wands, and puts two blessed scrolls of magic mapping into your inventory.
• The Archeologist home level contains another encyclopedia.
• There has to be an incentive for archeologists carrying around their encyclopedia so it doesn’t just get discarded as dead weight. A flavorful way to do this would be to award them extra experience points (say, double or triple) when they learn new object types while carrying an encyclopedia.

Implement “spoiler novels”, cheap books like 3.6 novels that contain spoilers. (Not described in what form the spoilers would be. Several true rumors?)