The only brands they didn't rebadge with were Pontiac, Saturn and Cadillac. However, I think the next most rebadged vehicles were the GM U Platform vans.
Chevy Venture/Uplander
Pontiac Trans Sport/Montana/SV6
Olds Silhouette
Buick Terraza
Saturn Relay
And built on the same platform were the:
Pontiac Aztec
Buick Rendez Vous
Not as bad nowadays since there aren't so many brands anymore.