I've been using my Python script in anger to help convert two chapters
worth of references from plain text references to Bibtex entries.
It's a bit rough and ready and assumes quite a bit about the layout of
the references in the plain-text text, but it did a kind of 90% job
Maybe it could be helpful for others too, but you shouldn't expect too
much of it.
Of course it could be improved a lot, but at some point, faced by the
law of diminishing returns, I decided to stop improving it when it was
doing 90% OK, and the rest (the difficult cases) I've edited by hand.