Neil Gaiman, one of the most creative writer who writes stuff out of nowhere, explains how he gets his ideas..
In the post, he said everyone has some good ideas. Some people will approach him with the idea and ask him to write for them, and split the money 50-50..
I'm reasonably gracious with these people. I tell them, truly, that I have far too many ideas for things as it is, and far too little time. And I wish them the best of luck.
Developers are akin to authors.
I too, keep a long list of ideas.