"Applying the "spec work" model that has long plagued graphic designers and writers to interviews won't fly with a great candidate that (correctly) values their time and knowledge.  Pay for the work on a per project basis, at the consultant's full rate, don't be one of those companies that just wants to "pick your brain for a minute" or just see what you can get for free. Just because something is a trend doesn't mean it's a fantastic idea or won't be abused." - Leslie Poston