In the Firefly fanfic Forward, Mal and Zoe start interrogating one of Adelei Niska's men because Niska has kidnapped River and Jayne and is torturing them For the Evulz. The morality of the situation is highly suspect; most of the crew find the apparent necessity horrific, and in the end it proves entirely fruitless, as the thug is more afraid of Niska than he is of Mal. It isn't until Book drugs the man and Wash talks him into revealing information that they get anything useful.
You Obey makes very effective use of this trope. It's actually subverted in that the interrogator really doesn't want to have to resort to it, vastly preferring less disturbing and more reliable methods.
24: The Musical, a fan-made musical version of the show's second season, parodies and lampshades this by having Jack sing "Torture and killing / They're par for the course / Sometimes there's no other way / You want results / You gotta use force / This is the longest day of my life!"
In Child of the Storm, it's pretty much stated that Loki, who is Reformed, but Not Tamed, indulges in this when he really needs to get information out of someone fast. Practically speaking, it's far more effective than most examples of this trope because he can tell when people are lying. Morally speaking, it walks a certain line, and most of the other characters find it disconcerting. One indicative example is in the sequel, when urgently requiring information, Loki threatens Sabretooth with removing his nervous system while he's still alive, stringing a harp with it, and playing a tune accompanied by his screams. This leads a rather disturbed Jack O'Neill to ask if they're sure he's not still evil - Jack's mother, former Deputy Director of SHIELD, simply remarks words to the effect that he isn't, but he remembers how to play the part. Subverting the trope, however, Sabretooth isn't remotely fazed by this prospect, until Loki whispers something in his ear and conjures 'an illusion or two', whereupon to general astonishment, he's very free with information.
In Slipping Between Worlds, British Army officer Lieutenant Philip Holtack attempted to subvert his Escape And Evasion training by asking the rational question "But there's nothing a trained interrogator cannot get out of a prisoner given enough time and effort. So what if I were to say Look, I'll tell you everything I know right now to save time, so we can both clock off early and spare a lot of aggravation?" This earned him a punishment from his tutors, who felt he wasn't taking things sufficiently seriously, and ultimately, a place on an SAS-level "resisting interrogation" course where things were ratcheted up to a level of nastiness he would not normally have experienced. This is Truth in Television: being "captured" and forced to undergo a mock interrogation under realistic conditions is part of training for many British service personnel.
In Revelations chapter 11/12, Túrante tortures another vampire to get information about the plans of the Big Bad. She had killed the rest, but left one alive for this purpose.
In Into The Hedge, Lero is heavily implied to pull this on a pack of soulless clones of the Cutie Mark Crusaders; who are young school-age girls.
HK-47 in The Havoc Side of the Force asks a crew member of the ship that attacked them a question. When she refuses to answer, he holds her outside the force field keeping the ship's atmosphere in until she almost passes out then asks again. Harry's mildly disturbed by this but doesn't let it show.
Subverted in The Headhunt. Lieutenant Dul'krah, Clan Korekh, security chief of the USS Bajor, draws a knife while interrogating a Mafia capo ... and then just sits there picking his fingernails with it, all the while just staring at her for over half an hour. Helps that A) he's nearly seven feet tall and "built like a Cardassian main battle tank" in his captain's words, and B) his species has nictitating membranes (i.e. he can make his eyes look lidless) and vertical slit pupils, so all he really needs to do is sit there with the knife and look scary. The fact that the capo can't escape, being shackled to the table, does the rest.
In Second Chances Loki tortures Balder until he mentions who made the magic dagger Balder stabbed Loki with.
In Susan Bones and the Prisoner of Azkaban Alastor Moody tortures Walden Macnair using only variations on the levitation charm, ranging from letting a levitated rock drop on Macnair's ankle to letting him drop from a height of seven or eight feet.
In Project Delta, when Jane realizes a pirate ship they have captured is working for the Red Wake, she burns the flesh off the captain's hand to make her talk.