Best advertising campaign of the last 15 years?

[J-Mac]

Note: I deliberately left the question vague with the adjective "best". "Best" could mean most successful in terms of promoting sales or brand identity, it could mean funniest, most memorable, most culturally significant, etc. I chose 15 years because it is the time span most familiar to most posters here, but it's largely arbitrary.

I submit that the most significant ad campaign of the last fifteen years is MasterCard's "Priceless" line. The process of listing items and costs and closing with the word, "priceless" has pervaded pop culture and the tagline itself is now practically synonymous with the company. Honorable mention to Nike's "Just Do It" line in the 90s.