According to Filius Flitwick the Fidelius charm is:
"An immensely complex spell involving the magical concealment of a secret inside a single, living soul. The information is hidden inside the chosen person, or Secret Keeper, and is henceforth impossible to find — unless, of course, the Secret Keeper chooses to divulge it. As long as the Secret Keeper refused to speak, You-Know-Who could search the village where Lily and James were staying for years and never find them, not even if he had his nose pressed against their sitting room window!"
So this charm is all about trusting someone, the secret keeper, to hide an information within his or her very soul. In this case the location of the Potters.
Does that mean the Fidelius charm is limited to hidding places? From your understanding of canon could it be possible to hide another type of information such as the incantation and wand movments of the unforgivables, the recipe of a dangerous potion or even the very existence of an indivual?
Thanks for your input.