Pensieve

A Pensieve is a fictional device in the Harry Potter series of novels by J. K. Rowling. A Pensieve is a stone basin, covered in mystic runes, with a fluid or gas within. A wizard can place their memories into the basin, when the mind is too flooded with information. One can more easily examine the patterns and interrelations of thoughts while they float in the Pensieve. The Pensieve also allows the user to fully immerse themselves in the memories stored within, much like a magical form of virtual reality.

A Pensieve first appears in Harry Potter and the Goblet of Fire, and again in Harry Potter and the Order of the Phoenix. There are many pieces of software that attempt to do what the Pensieve does, though as they have no magic to use, they're neither as visually striking nor as useful, as a "real" Pensieve. (A WikiWiki can be seen as one such thought-collecting program.)