Really intriguing question, and, even more important (to me, anyway), really, really interesting answers. Especially merlyn's answers about having to make a mnemonic for the nameable but unstoreable object, then storing the name as a hash key.

I still think of numbers on an X-axis, zero in the middle, positive numbers growing to the right, negative to the left. That's zoomed in, but zoom out a little and 1..10 seems to go up a slight hill and 11..20 seems to go down. I also see 'ledges' where you go up from 99 to 100.

Of course, behind some of the numbers are little packages of information, for example, behind 52 is: address of house in Baie D'Urfe, number of weeks in a year, number of cards in a deck, one more than 3x17, 5^2 backwards ..

And someone mentioned phone numbers .. I usually remember them by the pattern on the keypad .. for instance, a church might have the phone number 456-2580.

Cool question.