This is really a lot of fun. I tried soundex title, ignore author, and it finds very surprising things. I have a lot of books in French, and it matches these against the English titles (no surprise). I actually found 2 new duplicates. However, I am mystified why "20,000 Leagues under the Sea" matches "L'Assassin du roi".
@kiwidude: this is really good stuff. I suggest that you make it generally available as soon as you are comfortable with doing so.