I've started this here thread on classic promos for Nickelodeon.

One particularly memorable promo promoted "Actual Reality". An announcer started with "First there was video games, then there was virtural reality...", though I wonder, was it ever common for somebody to ahve a virtural reality console in their homes? Anyway, afterwards the home shown fell apart, revealing a basketball court when the announcer talked about "Actual Reality", which was actually promoting being outdoors and actually doing things. Back then I actually thought Actual Reality was an actual (pun not intended) product, giving me some confusion. Boy, was I ever wrong...

There was also a series of claymation shorts called Inside-Out Boy, featuring a boy whose body suddenly turned inside-out. The tagline here was basically that he had what it takes for (insert episode conflict here): "Guts!"

The Adventures of Pete and Pete also started out as a series of short promos before becoming ahalf-hour series.