Simpsons, The Easter Egg - Stonecutters Logo

In the episode "Make Room For Lisa" they got to a store called "Karma-ceuticles" and when they walk in, you get a full view of the store briefly, look in the upper-right corner and you'll see a red hanging banner with the Stonecutters logo on it.

The Stonecutters were a club of people Homer joined in the ep "Homer The Great".

Many cameos from previous episodes pop up from time to time. I know there's a lot more. Keep looking Simpson's fans!