Use Affiliates module by non registered users

Issue Summary

Use Affiliates module by non registered users

Hi,

I wonder if it would be difficult to allow non registered users to use Affiliates module by checking the referrer website as Marco does it on Toplist module ?

I think it's always easier to get people to link to your website if you don't ask them to register.

Toplist module:
http://drupal.org/project/toplist

Thanks for the great work !