Watch this American Express commercial for a perfect example of a sticky message. I guarantee that the message will stay with you, and the advertiser uses nothing more than simple images and music.
Of all the principles of a sticky idea, I think simplicity is my favorite. Presenting an idea simply can be a lot of work for the speaker in the preparation stage, but by the time it gets to the audience, they hardly have to work at all to understand it. Beautiful.
If you haven't yet read Chip and Dan Heath's book, "Made to Stick," I can't recommend it enough as a guide to creating unforgettable messages.