This is a good little video for Sunday. It's a brief look at the art and history of logo design.
I sometimes bash creative agencies for charging a large fortune for logo design - perhaps I shouldn't. It's certainly very hard work to create a corporate logo that will survive the test of time. We've had logos that have changed hugely - think of Apple's evolution from the Newton sketch through to the simple bite. We've also had logos that feel like they'll last forever - Coca-Cola being a strong example here.