And this does not include skits from shows like SNL, Mad TV and shows like those. That being said, some off the top of my head are:
The Family Heart Center (Robocop)
Magnavolt (Robocop 2)
Spatula City (UHF)
Central Services (Brazil)
Morrie's Wig Shop (Goodfellas)
The Empire Hancock Building (Cheech & Chong's Animated Movie)
Cox Sausage (Dewey Cox)
The Edge (Beavis & Butthead)
That microphone commercial from The Simpsons
I know more than those, but they won't come to me right now. ARRRRGH!