This is another easy post for me to write as well. My favorite (D&D) adventure is still B2 The Keep on the Borderlands. It's essentially a beginner's sandbox, and it's fun to play with: hooks of all sorts abound just using the material within. The DM can tinker to his heart's content. For example, when I run it in the future, I'm replacing the mad hermit encounter with Brave Halfling's The Vile Worm of the Eldritch Oak; it seems like a good fit.
My favorite time running it was a couple of years ago for the Guardians of the Polar Bear, aka my wife and kids. My son, who was 10 at the time, was running a Chaotic fighter (B/X rules in place), and the girls were running a Lawful Elf, a neutral elf, and a neutral dwarf. My wife was playing a Neutral thief. They infiltrated the goblin caves starting out (well, after clearing out the fens of the lizard men) and went straight to the "Bree Yark!" cave. After defeating most of the goblins AND the ogre (!), one of the goblins failed morale and surrendered.
My son's Chaotic fighter (Kane Deathchant, I might add) knew Goblin and decided to converse with the little chap. The elves and dwarf were all for killing the goblin (I must add, my wife was gone to a bathroom break; I don't know if she could have stopped the events that were about to transpire). Kane decided he wanted the little guy as a follower; the goblin's reaction was positive and he introduced himself as Adze-jakon, the lowliest of the low. Kane said he was not sure if he could remember that, so he'd call him "Deacon" instead.
The elves and the dwarf were furious; there was no way the Keep was going to allow a goblin, especially one attached to a fighter with the last name of Deathchant, to enter the keep. Will, to his credit, already had a solution worked out. The goblin could stay overnight in the lizard man caves that the party had previously cleared and Deacon could meet them on the road the next morning. The dwarf, however, had had enough talking and went over and hit the goblin with her axe. Kane drew on the dwarf and all hell broke loose! The Lawful elf backed out of the fight once the goblin was dead, but the other elf and dwarf still continued to fight Kane and he soon fell. Will, again to his credit, handled his first character death pretty well, and began rolling up another character (this was his second campaign, incidentally).
Meanwhile, the party (and the horrified thief who had just stood by while this was going down, because the player was on a bathroom break), in true murder hobo fashion, looted the remaining corpses including poor Kane. And, THEY LEFT HIS BODY IN THE CAVES!!! Upon returning to the Keep tavern, they were faced with Kane's brother, Bane Deathchant, a Chaotic magic-user, who was supposed to meet his brother at the Keep. The Keep's guards had told him that Kane had met with an adventuring party and went out with them that morning. The party prevaricated with the Lawful elf and the thief both wisely remaining silent (and facepalming!) while the other two explained that Kane had fallen in battle, but they were unable to recover his body and were forced to fight their way out.
Now, I had explained to Will that he could not act on player knowledge and had to act only on what Bane learned. What followed next is one of the best roleplaying sequences I have ever seen from either a young or new player. Bane wanted to recover his brother's body, and the party, led by the heretofore silent elf and thief (with glares at the other two) said that would be great and they would gladly assist.
Meanwhile, back at the Caves of Chaos, the goblin chief had learned that a guard post and his Ogre mercenary were dead. Now, in the Caves, any sign of weakness invites an attack so....the chief had the ogre beheaded and the head placed on a pole outside the entrance to the cave and HE HAD KANE'S BODY CRUCIFIED!!! He also had a sign (in Goblin and broken Common) placed around Kane's neck that basically read, "This is what we do to intruders and those who betray us."
This grisly sight met the party upon their arrival at the entrance to the goblin warrens the next morning. Bane was, naturally, enraged and the pogrom against the goblins began!
Until tomorrow, gentle readers, reminisce about your own adventures and days of yore.