4 years later, this post still comes up on Google. I emailed support to get my used Chumby activated, and it was done! But I was pointed in the direction of the new big orange button in the upper-right of the Chumby.com home page.

Or this big, blue link: http://www.chumby.com/my_chumby/deactivate

So, yeah... sometimes the answer is to look first, Google later.