Builds that involve non-version-controlled files that exist only on a certain developer's machine, and because that developer is a control freak (or overworked), he refuses to automate or put those files in version control...
I believe this is called "Job security." I've seen it a few times including a dev deleting the source code repo and substituting all copy of a set of scripts he was responsible for with compiled binaries. This was discovered due to a platform incompatibility between one of the hosts running the script and the binary wrapping. Data was then restored from backups and dev was summarily let go.
