Hmm, I'll say that I don't necessarily get story ideas all the time, but definitely here and there over time xD I never ended up making anything of it, but I started a story idea back in middle school for a long fantasy epic, and man do I have sooooo many arcs and story scenarios for that bouncing around in my head. Some I wrote as assignments for creative writing courses in Highschool/College, some I wrote down for myself, and others are still just lingering in the back of my mind. If I ever do pursue creating that story I'll have a lot of material!
As far as new, unique story ideas... not super often. The one-shot I'm working on now took quite a bit of conscious effort to string the story together after I had a very general idea and characters made.
Just last week though I had a random spark of inspiration though. I was just at work and all of a sudden I was like "holy crap, I know what I want my next comic after this one-shot to be!". it's both good and bad xD On one hand, it'll be months and months before my current comic is finished, so I wont be able to do anything real with this idea for a long while yet. But on the other hand, I'm going to try and generate some of the story in writing in the meantime :] so hopefully when I get to the point where I can work on it, I'll have a decent amount of material to work with!
So that was kind of a happy surprise xD Not necessarily a common thing for me though.