Need a plot for your RPG that you are planning to create? Try out The Big List of RPG Plots, by S. John Ross, who has neatly and quickly summed up many many an RPG plot line. Try one on for size?
Quest For the Sparkly Hoozits
Somebody needs a dingus (to fulfill a prophecy, heal the monarch, prevent a war, cure a disease, or what have you). The PCs must find a dingus. Often an old dingus, a mysterious dingus, and a powerful dingus. The PCs must learn more about it to track it down, and then deal with taking it from wherever it is.
Common Twists & Themes: The dingus is incomplete when found (one of the most irritating and un-fun plot twists in the universe). Somebody already owns it (or recently stole it, sometimes with legitimate claim or cause). The dingus is information, or an idea, or a substance, not a specific dingus. The PCs must “go undercover” or otherwise infiltrate a group or society, gaining the dingus by guile or stealth.