That's quite addictive.

The sites/pages that provide links to those images tend to disappear periodically 'cause people posting pictures complain about the bandwith usage from thousands of random users viewing the images. I have a private link version of that, which I use to generate a "picture of the day" for coworkers. Doesn't always work so well.

(If that URL goes away, ping me, I'll share an alternate URL.)