I'd love to see a engine plugin to use for instance the Linode API to add domains to their secondary DNS servers, setting the i-MSCP as the master:
This would optimally add and remove the domains as the were added to i-MSCP so that linode DNS could retrieve them from i-MSCP and serve as backup DNS. etc.
I'm sure there are dozens of similar services out there. The same model could be used for that.