Maybe you are on a long international layover? Maybe you have several hours before you flight home? Got to LA a day early? Despite the scary traffic, it is not hard to get to "The Getty". It is one of my favorite museums anywhere in the world, and it is free (except a small parking charge). You don't have to be a museum nut to enjoy it, the building, site and view are fascinating in and of themselves.
There is also the Getty Villa in Malibu, but you are supposed to have a reservation. If you don't, mention to the guards that you are in LA for only one day, and they will likely give you a free pass at the gate.
Give yourself 30-45 minutes each way from LAX to the Getty to be safe, but that can include parking, gas, etc. I once had an 8 hour layover, and had time to rent a car, drive up there, and visit for 3 hours or so. It was worth it. Given the time allowed, if I had tried almost anything else in the area, it would not have worked out. For instance, Beverly Hills, Hollywood, or the LACMA in downtown are pretty risky for traffic given even ample time contraints and are best saved for an entire day in the area.