Jason Schappert has a short post on MzeroA.com that is worth mentioning and referring to by those just learning to fly. His entry concerns a common question he and no doubt many other flight instructors and experienced pilots receive as to what types of charts or publications a pilot needs to have. Jason breaks down the charts needed into those that should be carried by visual flight rules or VFR pilots and those that should be carried by instrument flight rules or IFR pilots. For both VFR and IFR Pilots, Jason lists sectional charts and an Airport Facility Directory (AFD) as necessities. In addition, he writes that IFR pilots should also have an IFR Enroute and approach plates.
Furthermore, even though the miracle of modern technology allows some of these items to be available in electronic format, Jason mentions a story involving one of his students who brought his approach plates in electronic format for a flight only to have his batteries died during training. Moral of the story: A pilot should ALWAYS have a printed copy of any chart or publication handy.