Package Management Question

[drew einhorn <drew@technteach.com>]

I have a box with way too many packages installed.

I went through an exercise trying and rejecting a bunch
of packages and ports with custom flavors.  A whole
lot of packages were automatically installed to satisfy 
dependencies.

Now I need to clean up.

I'm looking for an easy way to identify installed packages
that are not required to satisfy the dependencies of other
installed packages.

-- 
drew einhorn <drew@technteach.com>
Technology and Teaching