I love the button in your domain management that lets me add all Gmail MX records with one click, but it would be even better if it would be adaptive to whatever I put in to the hostname field. I often need to create the MX records for subdomains (sadly google does not accept wildcards) and it would save me quite some work if I could create all 5 with one click for subdomains as well.
Or if you could edit the hostname as well for a record that would be a great alternative.