Here is my list of ways a spell book can be trapped. It's system neutral. I am not the originator of most of these, you may thank Anonymous. Enjoy. I should come up with a list of specific magical books later. . .
2. Explosive Runes
3. Contingency (To trigger any spell)
5. Dusty pages (spores, disease)
6. Contact poison
7. Twisted spells (harmful spells unless the caster knows the code or key)
8. Ink Golems
9. Cloud of a million papercuts (Targeting eyes, nose, and mouth.)
10. Something that looks like a linking book, but actually triggers an Imprisoment spell
12. A book with the same words on every page, with the spells coded into ink, or texture / material of the pages
14. Cursed (Polymorph for anyone reading the book who isn't the caster
16. Touching spellbook triggers a teleport trap
17. Spellbook has teeth
18. Touching spell triggers electric shock
19. When turning to a certain page (say 341) the book sucks the reader into it.
20. If anyone other than the owner holds it, it appears to be full of vile acts
21. Snake Sigil
22. Forcecage combined with monster summoning
23. Magic mouth (annoyance can cause a penalty to learn)
24. A book of random spells, one you turn a page, the previous page is changed.
25. Actual traditional (poison needle on lock) traps on the cover.
26. Pages made of flammable, acidic,or poisonous material when exposed to air.
27. Have some pages be explosive when exposed to air, and the cover be metal for shrapnel damage.
28. Animate object, causing the book to attack.
29. Trapped with a poverty geas
30. Yellow mold dust
31. Analine ink
32. Trap the soul in an object in a 'cutout'
33. Dimensional portal
34. A book bomb.
35. A book poison container
36. Cause feeblemind
37. A deadly creature inside a hollow cutout.
38. Animate object on nearby objects (clothing of the person who opens the book)
39. A book that leeches something from the user
40. A book that alters the user mentally in some way
A) gain a emnity to monster/race/class
B) gain a phobia
C) gain a mental quirk
D) gain an insanity
41. Book opens to a page that scrys on a location that shows a mirror of opposition or soul trapping.
42. Pages with razor edges
43. Fire trap
44. Something is bound to guard the book
45. Arcane mark would allow you to locate the stolen book.
46. Have some green slime or a black pudding permanently 'phantasmal forced' to look like a spellbook.
47. Have the spellbook located inside a safe (like a prismatic sphere)
48. Illusory script
49. Arcane lock on a mundane lock
50. A lock lurker
51. Disguise it using 'item' and 'magic aura'
52. Spells scribed incorrectly to fail or backfire
Any additional suggestions will get added to the list.