Some thoughts on story idea generation

I've been intending to get back into the habit of writing in this journal. I have written some in paper journals, but mostly for my own benefit and nothing of interest to anyone else. But I just started journaling in Scrivener, which I'm also using for my current novel-in-progress, and found I really like it. It makes a difference now that I have a MacBook Air (thank you, Indiana Arts Commission, for the grant that allowed this purchase). It's lightweight and portable and I can take in wherever I go. Though I know lots of people swear by writing on real paper, I'm not good at indexing and keeping track of what I wrote where or in what month or year. The real benefit, I think, of Scrivener is it is so easy to tag by keyword, organize, and search, and even link to relevant web pages. In short, something like Livejournal, but for my eyes only.However, I would like to maintain this public journal as well. Today I began brainstorming a new story, and it's really exciting. I sometimes despair that I'm just not good at coming up with workable story ideas. I mean, I can come up with ideas, but are they "wow" ideas or something that, if written well, will be a pretty ok story but not much more?I think my real problem is going from the "what if" to the actual story premise to the plot. I've got lots of interesting "what ifs" floating around in my head, but it sometimes takes a long time for one of them to ripen and I can see a story there.For instance, I know I had the idea "what if an opera singer died, and they took our her larynx and hooked it up to a machine so people could still hear her voice?" I had that thought, wrote it down on an index card, but it took me months to figure out the story in that. At first it was a sort of "Emperor's New Clothes" type story in a rather short first draft, then later I found the story in the story which dealt more with issues of identity and how to cope with having strong drive to excel artistically but a mediocre talent. I wrote something that, after revision based on some great critiques, got an Honorable Mention from Writers of the Future. I haven't sold that one yet, but I have received personal rejections from senior editors at three different SFWA-qualifying markets. Not the same thing as a sale, but at least it's getting passed up there.The "what if" for this as-yet-unnamed story has been percolating in my back brain probably for years. It seemed it could be taken as sacrilegious, which in and of itself didn't bother me, but it seemed more like a gimmick suitable for a silly humor piece, and I'm not as interested in that.Then today I thought of a way I could incorporate it into a story with a little more meat on its bones, a story that would maybe seem shocking to some but would definitely make the reader think. I've even got a one-sentence pitch for it, which I'm not going to give away here. :)The next step for me is to brainstorm it, which I did in my new Scrivener journal. I didn't so much start writing the story or start writing an outline as much as just writing stream-of-consciousness about what I wanted to do with the story, who I think my protagonist is, what I want to say with it (theme), the fact that I need some major threats and obstacles for my protagonist to avoid making the story too cerebral and not visceral enough, etc. I think it will be a one-act story with a struggle for the protagonist that ends in him having a rather startling (I hope) revelation that leads to a major change of heart. I've got a murky idea of the ending and wrote a couple possible lines. I identified some things I need to research and thought of a couple people I know I can use as sources for this.I wish I knew how to streamline the process of going from the "what if" to the story. I suppose I just have to give the creative part of my brain license to noodle on an idea for a while. At any rate, I'm excited about the story and expect to mull and brainstorm for a few more days and then get to the writing!