Synesthesia

According to that fount of info, Wikipedia, Synesthesia is "a neurologically based phenomenon in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway." If you watched House last night, you already know what I'm talking about. Boiled down it's seeing sound or hearing colors. The picture I've included is how someone with synesthesia might see written letters and numbers.

Why do you care, you ask? I'll tell you why. (You knew I would.) Synesthesia can make for some interesting writing, when applied with a little deft. It can create some truly memorable descriptions. A synesthetic metaphor is a metaphor that suggests a similarity between experiences in different senses. Ex: Macy's offered a buffet of clothes.

Examples: A loud shirt, a bubbling-hot stench, shadows brushed her skin like feathers, damp morning light, the dark red scent of blood

See what I mean? Think of how you can use this in your own writing to increase the impact of your descriptions. Try to come up with your own examples - post them in the comments if you do, I'd love to hear them!