Well, many many years ago, back in the 80s, I based an NPC loosely on the peasant Dennis from Monty Python & the Holy Grail - you know, the "Help, Help, I'm being repressed!" guy? I didn't exactly do the same lines, but he was an outspoken communistic type with a chip on his shoulder. Almost 20 years later, at one of my former player's wedding in early 2003, he even remembered that NPC...
In a few Forgotten Realms games I was involved in, our PCs met either Elminster or Lady Alustrial (sp?) of Silverymoon. One of the other PCs even tried to hit on her, to which she reacted kind of bemused.
Another time, in a side adventure in a long term fantasy campaign, our DM sent us to another plane or alternate reality (or, maybe a distant past or future... he never really told us)... but, it was prior to the Star Wars-Phantom Menace coming out, and he had our regular D&D PCs encounter a small rebellion against a powerful, evil empire - complete with stormtroopers & a bad guy based on Darth Vader.