I love the ad where the dog comes in and lies down in front of the fire, followed by the cat, followed by the mouse, and then the cat kisses the mouse. I can't remember what it was advertising, probably gas or electricity. I thought it was very clever.
BBH (ad agency) have a reputation of doing good ads. They did a lot of the Levis ads including the 'Heard it on the Grape Vine' ad with the bloke who undresses in the laundrette (the song was actually a sound-a-like cover and not the original fact fans)
Carling Black Label (years ago before it changed to simply Carling). They did loads of good ads for years and years across lots of different themes. But there was one in particular that I remember where it spanned multiple advert slots with fake ads for music or washing powder but in all of them a cowboy would appear then be chased by a whole load of indians, completely trashing each ad set as they went. It was brilliant.