I've been noticing that typing errors can provide some interesting material for conceptual slippages, especially in very skilled typists (like myself, I daresay). When I'm typing quickly and trying to express a thought, not focusing so much on the mechanics of the typing, some interesting types of errors occur. Specifically, the substitution of symbols for similar looking or sounding ones. I have typed a zero on the number pad instead of an "o" on multiple occasions. The zero above the o on the keyboard would be unremarkable because of their proximity, but the zero on the number pad is quite distant!
Another interesting error is substituting the phonetic equivalent of a symbol. I just typed "vertue" instead of "virtue," presumably because that first 'i' in virtue is typically pronounced much more like an e, as in 'ver.'
Its an tiny bit of interesting insight into the subcognitive processes underlying the action. I wonder how this sort of approach could be formalized and tested (if it hasn't already been)? What clever things could you do online?