A more sane version of the Thought Bottle (it only stores memories). I should say that I copied the text below from another webpage, for what looked to be a different game than D&D, but I didn't save a link.
This item usually takes the form of a metal flask similar in appearance to an efreeti bottle. Bottle and stopper are usually engraved with intricate runes. The bottle can be used to store and protect important memories and thoughts, and is often used by powerful characters as a way of managing their (potentially cluttered) memories.
To use the bottle, a character concentrates on the thought or memory to be stored. He then uncorks the bottle and speaks the word of command. The thought or memory is then transferred from the character's brain into the bottle. All details of the thought or memory are held within the bottle. The caster remembers the general nature of the thought ("Oh, that was my thought on the design of an efreeti-powered steam engine") but need not worry about forget- ting specific details, since these are trapped in the thought bottle.
To retrieve a thought, a character uncorks the bottle and speaks another word of command. The thought or memory is then transferred directly into the user's brain.
Thought bottles are sometimes used to protect vital information. A messenger carrying vital plans through enemy territory where there is a significant chance of capture and subsequent interrogation might carry all sensitive plans in one or more bottles. The messenger does not know the contents or the command word and therefore cannot reveal the contents of the bottles. Likewise, a spy could gain secret information, transfer it to a thought bottle, then use forget or modify memory to wipe this information from his mind. After this, regardless of the methods used, the spy is incapable of revealing the sensitive information.
Thought bottles are sometimes used as "memory archives," where characters can save memories that are "cluttering up" their minds. (This would be more of a problem for long-lived races such as elves, since the sheer volume of memories recorded over several centuries could be overwhelming.)
Thought bottles will function (in both storage and retrieval) for any intelligent creature.
When discovered, 75% of all thought bottles can hold only a single thought or memory. The remaining 25% have a capacity of 2d4 separate thoughts or memories. There is a separate word of command for each "thought slot."
Market Price: 2500 gp
Prerequisites to make: 1250 gp, 500 XP, Steal Memory class feature
An alternate version which is capable of holding all the memories of a person (up to 1000 years) is 5000 gp.