debian-control-mode, although there is hardly any code left from it now. It only features syntax highlighting for now (including warning for licenses which were not on the wiki page at the time of the writing, or were marked as needing more discussions) but, after all, this is only my first emacs major mode...
The code can either be downloaded there, or from my
bzr repository, in the
bzr branch http://people.debian.org/~fourmond/bzr/scripts
No debian package for that for now, as anyways it really should integrate
dpkg-dev when it has matured somehow. Hope this helps !