Dummy Data Creation Utility

OK, been working on a line of business app for one of my clients and I have gotten to the point where I need to do some real world testing. The app is pretty small; something like 40 tables in the db but it will expand pretty rapidly. How can I test this thing with a bunch of data in it? So I threw together a lil utility that will call the stored procedures and pass in dummy data; worked great, in a few minutes I was testing with 500K+ rows in some of the tables; an important thing to do, something often overlooked.

So here is my thing, I wonder now if this is useful...teaching the app tables rather than stored procs would be easy but it would be slick if I could make it understand keyed relationships…?!?

So let me know, is this something useful? Is there something already out there? Am I insane for wasting a couple hours on this?