Potentially a mammoth project.  As Abby points out, there would inevitably be some duplication of work done at the Ballad Index; on the other hand, it could be an extremely useful resource in its own right.  There's a case, I think, for putting something like that on a separate site, linked here in the same way as Alan's midi site; it could easily become too big to be accomodated on a thread here.  I've recently begun to index the songs in the books that I have at home, (using a spreadsheet, so that I can display by song or by collection) -at barely a third of the way through, I'm already nearly up to 1000, and I have but few songbooks compared to a lot of people!  I'll be happy to make my lists available to you (in whatever form you decide to use) if that would be helpful.

Malcolm