Well, it doesn't really need to be a "webapp" per se. You can write it in PHP and call it from the browser. It doesn't even have to output anything. And you don't really need to output it as an SQL file either, you can do the inserts on the fly. Of course, as usual it comes down to each to his or her own. Me, I do all my shell scripting in PHP. But then I'm a freak like that.
Jean, there's no tool out there that I know of to perform the conversion automatically (although I would be surprised if there isn't one somewhere). I would suggest that you write one and release it. 🙂
adam