This is a really nice idea and I'd love to see it in another implementation.
I'm a shortcut junkie though so I completely love the idea of a personalised DNS server that learns what I commonly resolve and allows me to make shortcuts.
Have you ran into any issues with it hosing your /etc/hosts file at all?
m -> mail.google.com
m1,m2 -> mail.google.com/mail/1,2/ (1 or 2, not both)
cr -> github.com/sprintly/sprint.ly/pulls (cr = code review)
docs -> docs.google.com
c -> google.com/calendar
We had this system when I worked at Google (it was probably DNS as my hosts file wasn't altered) so I got really used to going to c/ when I wanted calendars. :)