Actually I'd go for Lucy and Ethel...
Just a few off the top of my head:
Tom & Jerry
Ralph Kramden & Ed Norton
Buffy & Angel
Fry & Leela (Futurama)
Bread & Butter
Toast & Jam
Coffee & Cream
Corned Beef & Cabbage
Ham & Cheese
Apple Pie & Ice Cream (yum!)
Gin & Tonic (unless you don't want to bring up alcohol)