Slashdot linked to an amazing online exhibition at the American Museum of the Moving Image a while ago, but it of course had been slashdotted. I just happened across it today, and can't recommend it highly enough.
"The Living Room Candidate" is a collection of television ads for presidential campaigns from 1952 to 2004 and is truly amazing. It serves as a simultaneous documentary of American politics and the history of television in the past 50 years. Insightful and unbiased commentary on the elections, issues and individual spots allows you to trace the important events in national identity over half a century. And as icing on all the great content, the site is well designed and implemented, and totally ad-free—well, except for the campaign ads.