I've encountered three types of spelling memories in my time. That is, three different ways of remembering the sequence of letters to correctly spell words. I am personally a visual speller: the shape of the word looks right to me. Some people I'm aware are auditory spellers: the letters sound right when read out. I have just recently encountered a muscle-memory speller: words feel right when written out cursively. I find that quite interesting. I can't think of any other possibilities, but then I hadn't anticipated the muscle-memory one at all.
Mokalus of Borg
PS - Perhaps some people can smell words.
PPS - I wonder if Braille can "feel" like it's spelled correctly.