Random image generator from public photosharing sites API?

I was wondering if anyone knows of a way to get a public image from Flickr, Picasa, and others.

I attempted to look through the Flickr API, but all I found was a way to display a static image. I also found a way to retrieve an 开发者_开发技巧image from a specific user, but I want a way to get a picture that has public licensing.

Picasa API, however, was even harder to look through.

I know that I would have to use JavaScript to have it auto-refresh about 20 seconds, but I don't know (or care) what I need to use to fetch and display the pic.

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http://randomimage.setgetgo.com/