The Beach Boys played the music and sang backing vocals on Jan & Dean's cover versions of Surfin', Surfin' Safari and Little Deuce Coupe. Brian sang backing vocals on Surf City, Drag City, Dead Man's Curve (the album version, not the hit single version), Ride the Wild Surf, Gonna Hustle You and Vegetables.
Interesting story about Surf City... When Jan & Dean first heard Brian play Surfin' USA, they asked if they could have it. Brian wanted to save it for The Beach Boys, but he didn't want to be unkind and gave them Surf City instead. It went to #1. Murry Wilson was furious at Brian for giving his first #1 composition away.