Sharing photos online easily

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I'm looking for a site where I can create multiple albums so that our class can view and share pics online. It should be free, easy to use and not crammed with ads. Would prefer one that has no flash. Would love it if it auto-resizes the photos. Most importantly people can view the pics and download/save them without having to create a account or login so viewing is instant. Will need the ability to create multiple albums too. I know webshots and kodakgallery - but are there any better ones?