I think I may have color–grapheme synesthesia. For the most part, I don't pay attention to the colors that I perceive in letters and numbers. But then I read an article like this, which quotes someone during the colors they see, and a voice in my mind shouts, "That's not the color of L!"

As a tangent, I wonder if there is any association between color–grapheme synesthesia and spelling or reading ability. I work as a kindergarten and first grade teacher, so I have the pleasure of guiding many young minds of all kinds as they begin to read.