pkg-orphan is a console utility for managing orphan, i.e. unreferenced FreeBSD
packages. It finds all or selected orphans and lets the user choose which ones
to remove and which ones to keep. It maintains a keep-list file, so previously
kept packages will be skipped automatically. In batch mode, all packages, not
present in the keep-list are either deleted or kept in the list.

Since orphan packages are usually much fewer than non-orphan ones, it can be
useful for quickly finding and deleting unused packages, even on a system with
hundreds of them installed.

Features:
 - interactive and batch modes
 - maintains a kept package list, to avoid asking for the same package again
 - can delete packages recursively, but without deleting shared dependencies or
   previously kept packages
 - the keep-list file does not contain package versions, so upgrades generally
   don't require editing of the file

WWW: http://sourceforge.net/projects/pkg-orphan/