I've been thinking a lot about this lately- especially in relation to how the human mind works. When we see something or read something, we have an innate ability to classify and store that information for future retrieval. Not only that, was associate it with other existing information and create synaptic links between the new data and the old. We add contextual information around it- where we we at the time, what we were doing at the time and who we were with... We all-but discard the information (not sure how much this is true...) if it is not deemed relevant. Sometimes we can bury information that is too painful or too distressing and invoke an amnesiac response.
The problem is, we all do this in our own distictive styles- we develop our own retrieval system- some use mnemonics to help retrieve complex data, others use rhymes. Most people use calendars or other external 'props'.
This is what's been on my mind a lot lately. I guess you can make your own links to what I'm thinking about next...