Binary package “deborphan” in ubuntu precise

program that can find unused packages, e.g. libraries

 deborphan finds "orphaned" packages on your system. It determines which
 packages have no other packages depending on their installation and shows
 you a list of these packages. It is most useful when finding libraries,
 but it can be used on packages in all sections.
 .
 This package also includes orphaner, a text menu frontend to deborphan.
 Please install the recommended packages dialog, gettext-base and apt when
 you want a working and fully featured orphaner.