What inspires you as a GM when you write your adventures? For me, I do generate a lot of my own content inspired by stuff, but I recently had an idea for an adventure which combines Black Swan and the King in Yellow. I even considered a punny tagline: "A dancer seeks a way to break into the big time on the stage, but instead tears a hole in reality."
Like, I'm a horror-based GM, particularly the psychological aspects of it. If I can make the players at least relate to their character's fear, I consider it a good adventure.
I run completely sandbox campaigns (usually), but I do have set adventures ready for whenever the PCs stumble into them. While my world design is almost always inspired by games, I pull adventure ideas from anything I can. I typically use online plot hook generators for the basic type of adventure (investigation, hostage rescue, high profile theft, grave robbing, etc.) then I go to films, anime, live-action tv serials, games (again), published adventures, and whatever else I can to help me fill in the details. Usually, I only need a basic adventure type and the details pour out like rain; during dry months I ravage my movie library, bookcases, previous campaigns, and the internet for any inspiration I can find.
Also, Chaotic Shiny, has proven useful more times than I can count.