Museum of Mario
I hate to talk too much about Mario since I'm not really much of a gamer anymore, but IGN recently put up a Museum of Mario HTML5 webpage that is a great use of newer web technology to create an interactive and entertaining experience. It's a fully responsive design, which is fantastic considering that there is animation going on. It seems to work best using Chrome, but Firefox works fine and I'm assuming Safari is too. You're on your own with IE, since I don't use it.