We had a sandbox account log in at the registration page, but after some testing we found that it made a lot of people who would have signed up just go to the sandbox instead.
You could generate a unique key for each visitor as a sandbox user and then give the prompt to convert to a full account once the user has started interacting with the site. Be sure to make it non-intrusive though.
The original page is here: http://www.ragic.com/intl/en/registerSandbox
For people who would like to use the sandbox instead.