Here are a couple more . . .

Updating the "American Beauty" entry

American Beauty - Annette Benning - Don't Rain on My Parade - Bobby Darin

Defending Your Life - Albert Brooks - Barbara Streisand - ?
Reality Bites - Jeanne Garafalo/Winona Ryder - ? - Tempted by the Fruit of Another
Godzilla - Matthew Broderick - Fred Astaire - Singin' in the Rain

Also, I just watched "Meet the Parents" and that entry should be removed as Stiller and Deniro are driving in the car but all Deniro says is "Puff" one time and then launches into a conversation, so it's not really singing.

Erik