When I worked in the corporate world, sometimes I'd devote a staff meeting to brainstorming. We'd have certain "rules." No interrupting. No judging. No making fun of someone's ideas. I'd stand in front of a flipchart with a Magic Marker and scribble down everyone's thoughts. And boy, did we get some interesting ones! (No matter how many times it was suggested, we never did go to a one-day workweek.)
After we were done generating ideas, THEN we'd gather again to evaluate them. Essential, but not nearly as fun.
Now, I use brainstorming to come up with story ideas. Big picture, little picture, in-between picture. Character traits, settings, plot points, titles (especially titles). It doesn't matter what I'm working on, I find that generating a list of possibilities helps me be more creative, and it helps me narrow down my choices at the same time (weird how the mind works, huh?).
I guess, to some extent, we all brainstorm, whether we call it that or something else.
Now I'm off to brainstorm future blog topics. (Any suggestions?)