I've used this technique myself in For Whom the Bell Tolls (Metallica) and Beneath the Willow (Brad Paisley and Allison Krauss). It is a top notch way to come up with new and innovative ideas. I've followed a link Moon sent me and wrote up an entire scenario, or string of scenarios from Metallica: Metallica.
End of the Road: (Inspired by They Might Be Giant's "End of the Tour")
Not three miles off the great rock coast lies an unexplained phenomena. Known as "The end of the road," it has become a site of great interest and fear in recent years. The title is somewhat of a misnomer, as no one can really tell whether the road is beggining or ending, instead being a mysterious, five meter long section of cobbled road, complete with the wear of carrige wheels. Many claim to have seen missing sections of road of about the same size elsewhere, and some even go as far as saying they have seen carriges along the road, then drop off passengers, though all reports remain uncomfirmed. The onlything known is that the road suddenly appeared there overnight, roughly three years ago. The one man known to be walking in the area, and therefore a possible witness of the events, has gone missing, many claim he drives an infernal carrige across the road on the anniversary of it's birth.
(Seeing as how this is a scroll I'm not going to go into "The truth," I'll leave that up to you) Go to Comment
A vicious murder happens in a town that the party happens to pop in at. Under heavy suspicion as they are strangers, the party is forced to discover the perpetrator or have their reputations blackened, especially as more and more murders occur in the town, and mysteriously stop and restart when the party leaves to go kill off that evil necromancer who kidnapped the princess.
The only problem is that a demon, possessing one of the party, is the perpetrator. And the demon makes no signs that its living in the PC's head.
In fact, for all the party knows (except for the possessed person's), their companion is an evil murderer.
Do they try and execute their friend as he's a vicious murderer, and no evidence points to demonic posession? Or do they flee town with him, trusting him, and have their reputations destroyed?