Thank you for your suggestions. We will definitely take them into consideration. We do have one concern with your second suggestion, though. There are actually 2 types of domain deletion.
One type is the grace period deletion which occurs during a domain's grace period (usually the first 5 days of registration).
The other type of domain deletion is the one that occurs _after_ the grace period (How do I mark my domain for deletion? - http://www.dynadot.com/help/question.html?aid=51). Here, we allow customers to submit a deletion request, but the domain will be deleted 30 days after such a request has been submitted. We cannot give an account credit for this deletion since the domain is deleted after the grace period.
Because we have 2 very different domain deletion features, I am not sure if it would be a good idea to place such a button on the "Manage Domains" page.