I once saw a documentary about a guy who claimed that numbers and such appeared to him as a kind of landscape, each number and letter forming the topography of this landscape (each with it's own colour, shape and texture). A collection of letters or numbers (such as a word or a math problem) would group together to form different shapes in the landscape. When he wanted to recall memories he would literally, in his mind, explore this landscape.

Of course people were skeptical, and he was put through a number of different tests, all of which he passed. I think their opinion was that this man was slightly autistic; not enough to effect his interpersonal skills and such, but enough to dramatically altar his brain functions.

He learned to read and speak fluently in Icelandic (or some other random, practically indecipherable language) in a less than a week.