Is there a way to add an Affiliate ID field at the wp-signup stage?

I am creating a network of blogs for people that will have customer banners with affiliate ID codes from other networks (ie: godaddy, etc.). I'd like them to be able to enter that ID in the sign up process, and then I'd like to be able to call it in a text widget box. So i'd add a text box widget, add an image, and the link would have the godaddy referral link (or any other company) and add in their id with something like "_YOURAFFILIATEID_"

Is this possible to do easily? Is there already a widget for this?