The way TV's going with all the new technology, I suspect that someday all advertising will be built right into the shows via product plugs and that we'll see an end to the interruptions once and for all. Still, there's something to be said for the folks who made those interruptions bearable by actually coming up with something clever and memorable to put in those ads.
Since we've already got threads on the best music videos, I say why not one for the ads? Most of the best ads tend to use humor to sell the product, of course, but horror can be good too. Here's a favorite of mine that employs a little of both:
So, how about it, people? What are your favorites?