A feature I would adore is auto nameserver, where you can set a default nameservers, so when you create a new domain it has your default nameservers. (Good for automated hosting like ClientExec)
This feature is actually already available (though it might not be easy to find at the moment). To set your default name server settings, follow these steps:
1) Log into your Dynadot account. 2) Click on the "Domains" link in the main menu. 3) Click on the "Advanced Settings" link in the submenu. 4) Click on "Default Name Servers" link under the header, "Default Contacts". 5) Enter in the default name server settings you wish to set for any future domains you register with us. (Transferred domains keep their current name servers as they enter your account, and will not be affected by these settings.)
Now any domains registered by us will be set to your default name server settings.