A long, long time ago? It has been a while. But it also isn't what I'm looking for. Aminator is designed for pretty restrictive situations where you're deploying applications (in the form of single RPMs). And I do a lot of that in what Aminator considers a base AMI, and that's fine...but what do I use to build the base AMI? =)

Packer has a lot of user-friendliness problems (destroying build artifacts on failure, as the OP noted, being just one of them), but it does constrain the universe sufficiently that I can just run Chef and get on with my day.