Anyone use postbacks to send information to a contact record. In my case, I would like to utilize a postback that I have access to that will notify us when a contact registers an account at a partner site.
Just to make sure that we're on the same page, are you referring to a form POST-ing to the same page on which it's submitted? You might want to consider creating a custom form to submit to the forms API; this will give you full flexibility around processing the submission and redirecting the visitor (or in this case, not).