BMW owns:
-BMW
-Mini
-Rolls Royce

Daimler/Chrysler owns:
-AMC (brand discontinued)
-Chrysler
-Dodge
-Eagle (brand discontinued)
-Hyundai (Daimler/Chrysler only owns 10%)
-Jeep
-Maybach
-Mercedes-Benz
-Mitsubishi (Daimler/Chrysler owns 37%)
-Plymouth (brand discontinued)
-Smart

Fiat owns:
-Alfa Romeo
-Ferrari
-Fiat
-Lancia
-Maserati

Ford owns:
-Aston Martin
-Ford
-Jaguar
-Land Rover (bought from BMW)
-Lincoln
-Mazda (Ford owns 33% of Mazda)
-Mercury
-Volvo cars

Fuji Heavy Industries owns:
-Subaru

General Motors owns:
-Buick
-Cadillac
-Chevrolet
-Daewoo (GM owns 44%)
-Fiat (GM owns ~20%)
-Fuji Heavy Industries (GM owns ~20%)
-GMC
-Holden
-Hummer
-Isuzu (GM only owns a percentage)
-Oldsmobile (brand discontinued)
-Opel
-Pontiac
-Saab
-Saturn
-Subaru (GM owns 20%)
-Suzuki (GM only owns a small percentage)
-Vauxhall

Honda owns:
-Acura
-Honda

Hyundai owns:
-Hyundai
-Kia

Nissan owns:
-Infiniti
-Nissan
-Renault (Nissan owns 15%)

PSA Peugeot Citroen owns:
-Citroen
-Peugeot

Porsche is an independent company (they do work very closely with VW, however)

Renault owns:
-Nissan (Renault owns 44%)

Toyota owns:
-Lexus
-Scion
-Toyota

Volkswagen owns:
-Audi
-Bentley
-Bugatti
-Lamborghini
-SEAT
-Skoda
-Volkswagen