A possible strategy for maintaining a verified association might look something like this:


 1. Gather a reference account from the user, similar to http://soapi.info/findusers.aspx, and upon user selection.
 2. Gather and verify an email address from your user. 
  - make it clear that this email address should be the primary email address with which they sign into stackxxxx
 3. compare the email_hash of the selected User to the MD5 hash of the *verified* email address (lower cased) and if a match occurs, create the association on your site.

You now have a verified association. You can then use the association_id, if any, of the reference user to get any other accounts the user may have in the stack exchange network.

NOTE: you will soon see an example of this in the samples for [Soapi.CS][1] and [Soapi.JS2][2]


  [1]: https://stackapps.com/questions/386/soapi-cs-a-fully-relational-fluent-net-stack-exchange-api-client-library
  [2]: https://stackapps.com/questions/1433/soapi-js2-a-fully-relational-javascript-client-library-for-the-stack-exchange-a