Steven Johnson is the author of 2 books about creativity: Where Good Ideas Come From, and The Invention of Air. He wrote an article about what he calls a Sparkfile, which is just a list of ideas.
He writes down every idea he has in this Sparkfile, and once in a while revisit it to see if there’s anything of value, or ideas he could combine.
That was more or less what my scratchpad was for. Blog & note taking kind of thing. I need to post more ideas in here.