I've already cleaned my world file of dependencies with udept, so searching through world won't reveal much.
Wolfden, your previous post where you listed all the packages you uninstalled is very helpful. Those types of tutorials on how advanced users use Sabayon are extremely useful to people like me who are new but want to become power users eventually.
My next question is how do you know you don't need those files? Is it just reading descriptions of the packages and learning more about what each one does? Is this knowledge you've just accumulated over the years of using linux/gentoo? It may be that there's no real shortcut for what I'm asking, that I need to just learn about what each package does to know if I need it or not.
I guess what I was hoping for was something like a script or process you could use to remove unneeded files, similar to what --depclean does with dependencies. So i would:
remove unneeded hardware/USE from make.conf
do something that would flag any programs/libs that depend on support that was no longer there.
Then I could go through that list and emerge -C any/all of them.