This one was elevated to the top of the list both because it was so funny and so memorable. One of the best commercials at generating talk at the office water cooler the next day, it featured a linebacker from Reebok recruited by a company's CEO to boost productivity.
The commercial is filled with a series of brutal hits as Tate lays the smack down on some cubicle drones. His hits, punctuated by lines such as "Break was over 15 minutes ago, Mitch!" made it so you couldn't help but remember this ad, even as you were flinching, then laughing, while watching it.
Honorable mentions: Emerald Nuts "Robert Goulet" (2007); Pepsi "Apartment 10G" (1987); Pepsi "Diner" (1995); Pepsi "Sucked in" (1995); E*Trade "Money Out the Wazoo" (2000); Careerbuilder.com "Monkeys" (2005); Tabasco "Mosquito" (1998).