From the Gulag Archipelago:
1. night - a newly awakened prisoner has reduced judgement
2. persuasion - convincing them that they faster they give in the better they'll be treated it effective
3. foul language - some people have strong aversions to swearing
4. psychological contrast - good cop, bad cop
5. preliminary humiliation - humiliate prisoners before interrogation: strip a woman naked, lock her in a box and have male guard peep in and praise her loudly and while laughing
6. confusion - one female interrogator stripteased in front of a prisoner
7. intimidation - threats, etc.
8. lie - to mother: "If you don't tell us such and such, it's going to be the worse for him. You'll be destroying him completely. Signing this paper is the only way you can save him."(destroy him) forged documents, etc.
9. playing on one's affection - sign this confession, or we'll hunt down and murder/kidnap your loved ones
10. sound effects - stand twenty-five feet away, forced to speak more and more loudly. OR, two interrogators bellow through megaphones into prisoner's ears, "CONFESS, YOU RAT!"
11. tickling - self-explanatory, simple but effective
12. cigarette put out on accused's skin
13. light effects - bright blinding light, no light, strobe light
14. imaginative trick: a prisoner was in the constant state of being LED to interrogation. go to room, go to cell, go to room, go to cell, etc.
15. box - confined space, mind tricks
16. discomfort - sitting on a stool not allowed to move, lean, sleep, etc.
17. divisional pit - a pit for prisoners
18. stand on his/her knees - this can break some people as the feeling of being dominated. one Soviet interrogator pissed on a man's face
19. stand there - just stand there. nothing else. no sleeping, eating, or drinking
20. deprived of water - no water at all
21. sleep deprivation - have someone run in, make noise, beat them, etc. when they nod off
22. assembly line - have multiple interrogators come in in shifts to interrogate
23. punishment cells - ex. room filled with bedbugs, extreme cold
24. locked in an alcove - combined with dripping water on head can cause amnesia and blackouts
25. starvation - no food
26. beatings - a swift kick to naked balls can cause unconsciousness, even bursting eardrums. also solar plexus hits, face punches, etc.
27. fingernail removal
28. strait jacket
29. breaking the prisoner's back
And these were just some of the Soviet Russian's interrogation techniques. Perhaps add a few?