I've gotten myself fairly familar with what products I need for keeping my paint looking great, but what about the other essentials like windows, wheels, tires, wheel wells, weatherstripping, chrome, plastics, engine/undercarriage?
Right off the bat, I thought of my two indespensable mainstays- Eagle One A to Z for cleaning tires, wheels and wheel wells; and good old Meg's #40, for treating all that vinyl and rubber. Those are two products I'll _always_ keep on my shelf.