Breyers
There was a series of ads featuring Bernadette Peters in the early 90s. For many years, I couldn't find them online, but finally I did find two of them (though the recording quality isn't very good). Wish I could find more. Much more recently, there were a couple of ads featuring Jane Krakowski dreaming she was in movies (Gone With the Wind, King Kong). I can't find them on YouTube, but they're on DailyMotion.
Häagen-Dazs
Halo Top
"Ice Cream for Adults" (This is a playlist but I don't think I can embed it, so... just click it, okay? It's funny.)
Klondike
Chemistry; Very little known bedtime stories.