I can think of two:
The first happened in a Shadowrun game I was running. The party has been hired by Renraku to investigate a cyber-terrorist that has been Black IC-ing legitimate users of Renraku headware and cyberdecks. The IC (a variation on Black Hammer) basically only attacks hardware that is encoded with a Renraku ID code. The decker in the group (Penna) is particularly worried, as her entire C-squared deck (internal cyberdeck layered DIRECTLY onto her brain) is made entirely by Renraku. So, after undergoing lengthy (and highly illegal) procedures to scrub out the Renraku ID codes, she begins the search for the terrorist, simultaneously crafting a deceptively elegant trap. The group eventually figures out that the terrorist and her cronies (who have destroyed an entire apartment building to try to kill the players) are actually hiding INSIDE the Renraku Arcology, and are tapped into the Central Mainframe which generates the ID Codes, guaranteeing that they can always tailor the Black Hammer for the latest cyberware. Penna arranges for a (mock) secure internal node with a bottle-neck access to be set up within the Renraku Mainframe, and leaks that Renraku has developed a new algorithm to create ID codes that the Black Hammer can't attack. Naturally, the terrorist tries to break in to get the algorithm. Penna plants her cyber-persona at the bottleneck and battles the terrorist, and loses on purpose, using her very high Deception rating to fool the terrorist. The terrorist rushes past her and unleashes the Black Hammer on the secure node, at which time Penna turns and attacks with a simple Hog program. Unlike most Hog programs, which just write babble that takes up an increasing amount of memory, THIS Hog program wrote line after line after line of Renraku ID codes. The Black Hammer turned on the terrorist, and laid waste to her entire deck (and the mind plugged into it). This fight, combined with the physical assault that the rest of the party led on the terrorists' hiding spot, was one of the best climactic fights I ever ran.
The other one was even simpler, and it wasn't the character using Bluff on the NPC's, it was the Player using Bluff on the DM! We were playing Call of Cthulhu, and we were trying to stop a ritual that would have summoned some very nasty critters into the middle of Central Park (using the Egyptian Obelisk as a focus point). Needless to say, we were just as worried about the police as we were about the cultists, but we didn't have time to bribe them or get them on our side. As we got there, we saw the cultists fanning out to take their positions, so we had no chance to take any sort of tactical position. Suddenly, Rick (our leader) said "My character runs towards the high priestess, firing his weapon!" He hit one or two cultists, and drew the direct attention of the priestess. After one or two rounds of combat, he gets hit with a powerful magic spell and goes down. The NEXT round, when the DM asks us what our intentions are, Rick just says "I play dead." The DM, familiar with Rick's luck when the odds are against us, as well as the fact that Rick's character has had YEARS of in game experience and very well could be resisting her magic, has the high priestess use her turn to attack him again. The next round, the same thing: "I play dead," followed by a magical blast into him. This goes on for about five rounds, during which we manage to mop up the minor cultists with only one fatality on our side. Finally, the DM says, "How many hit points do you have left anyway?" Rick just looks at him with a lopsided smirk and says, "Oh, I was negative from that first magic blast. I'm betting they'll have to ID my body by my teeth."