My idea is a gauntlet (a science-y one, not a magic-y one) with a blue stone built into the palm. Whenever its worn, and the stone makes contact with another person, all of the user's memories are uploaded to the subject's brain, literally frying their own in the process. The outcome of which, is the subject believing, for all intents and purposes, that they are the person who just used the gauntlet, and are suddenly in a new body, while unfortunately retaining their own memories, making them unsure of who they actually are, until they look in a mirror, provided they're too similar to find out by just looking at their hands or some such.
the testing logs would work out as follows.
As said above, subject one pours their memories into subject 2, leaving subject 2 in a panicked state of confusion, unsure of who they are, despite the help provided by watching Foundation doctors. Subjects of contrasting races, genders and builds are all tested on, with the same results.
A subject uses the gauntlet on a subject who has been dosed with maximum strength amnestics, practically leaving them a vegetable. After transfering memories, the subject vaguely remembers the brief minutes following amnestic application, but otherwise has flawlessly transferred bodies. It's speculated that the gauntlet could be used to give vital Foundation staff members eternal life.
A subject uses the gauntlet on a PC's exposed hard drive. The computer crashes and overheats. After the hard drive is carefully repaired, it is found to contain countless text documents, containing indecipherable gibberish.
Sorry if that's a bit long for the brainstorming section, but what do we think? Interesting?