Worst: Diet Pepsi: Brown and Bubbly. It almost felt like a big-budget, dirtier, nonfunny, unironic Popozao. In close second was the Buger King: Whopperettes. Wrong on so many other levels.
Best: Sprint: Locker Room (Crime Deterrent Cell Phone)
Runners-up: Bud Light: Hidden Bud Light and Budweiser: Superfan
Both iFilm and Google have collections of more of the commercials online here, and here.