They're creepy, hidden, and everywhere.

Subliminal messaging was actually banned from television, because from information from a CIA study entitled The Operational Potential of Subliminal Perception, if subliminal messages were used as political propaganda "they could be used to serve and maintain a form of totalitarian government." The CIA did a report that showed subliminal messaging were actually more effective than normal advertising.

We register so much unconsciously it's unbelievable. Every day just driving to work, billboards, shop windows, radio, other cars on the road, restaurants, etc. cloud our every thought unconsciously. Your brain actually processes things at 40 mph!

If you want to see something really freaky, watch this video: http://www.youtube.com/watch?v=ZyQjr1YL0zg

The first use of subliminal messaging was used in a theater with Coca Cola and Popcorn by simply flashing the messages "Drink Coca-Cola" and "Hungry? Eat Popcorn." The sales of popcorn and Coke went up dramatically after these short spurts of messaging flashing on the screen.

This is related to product placement. Look at the picture. See the Apple computer placed so subtly in this screen shot from the Fox TV show "24"? Bet that's the first thing you saw. Advertising is all about paying to get your product stuck in a movie, TV show, ad, or anything else to let the loyal audience (in the case of "24") know that the characters in the show use it, therefore it is a great product.