A friend of mine runs a catering company that does do business with a sizable group of Jewish people. Around this time of year she gets requests to be 100% Passover Kosher of course. This often leads her into doing research about "borderline" products (for example are Tortillas Passover Safe? Are Granola Bars?) but often she gets answers that work don't 100% of the time (Granola Bars for example may or may not be) from sources such as Google.
In short, what is the best method for determining Kosher For Passover status of a borderline food (or any for that matter)? Are Rabbis open to answering such questions (I'd imagine they get pretty bombarded during passover)? Did someone build a website www.isthiskosherforpassover.com Perhaps?