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You can also use a color as a subdomain: http://blue.bikeshed.com/ .

I've seen someone in a thread point to bikeshed.com, and someone else follow up with a joking "I think you mean preferredcolor.bikeshed.com".

Or any hex code it would seem: http://ff00f0.bikeshed.com/

You can also click on the bike shed image to change the bg-color.

And not only the bikeshed, the site's background changes too!