bedazzled@bedazzled ~ $ sudo emerge -C mozilla

--- Couldn't find mozilla to unmerge.

>>> unmerge: No packages selected for removal.

bedazzled@bedazzled ~ $ sudo emerge -C gstreamer

--- Couldn't find gstreamer to unmerge.

>>> unmerge: No packages selected for removal.

bedazzled@bedazzled ~ $ emerge --info | grep USE
USE="X a52 aac aalib acl acpi alsa amd64 avi berkdb bitmap-fonts bmp bonobo bzip2 cdr crypt cups curl dbus doc dri dts dvd dvdr dvdread emul-linux-x86 encode esd examples exif fam fbcon ffmpeg flac foomaticdb ftp gd gdbm geoip gif glut gnome gpm gtk gtk2 hal imlib jpeg ldap libcaca libg++ libwww lm_sensors lzw lzw-tiff mad mhash mikmod mime motif mp3 mpeg ncurses nls nptl nptlonly nvidia ogg oggvorbis openal opengl pam pdflib perl png posix python quicktime readline real samba scanner sdl sockets spell ssl svg symlink tcpd tiff truetype truetype-fonts type1-fonts unicode usb userlocales v4l vcd videos vorbis wmf wxwindows xine xml2 xosd xpm xprint xv xvid xvmc zlib userland_GNU kernel_linux elibc_glibc"
bedazzled@bedazzled ~ $ emerge -pvuDN world

These are the packages that I would merge, in order:

Calculating world dependencies ...done!
[ebuild  N    ] www-client/mozilla-1.7.12-r2  +crypt -debug +gnome -ipv6 -java +ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznoxft -mozsvg -postgres +ssl +truetype -xinerama +xprint 30,307 kB
[ebuild   R   ] gnome-extra/yelp-2.10.0  -debug -firefox* 0 kB
[ebuild  N    ] media-libs/gstreamer-0.8.10  -debug +doc 0 kB
[ebuild  N    ] media-libs/gst-plugins-0.8.10  +alsa -debug +esd -oss 0 kB
[ebuild  N    ] media-plugins/gst-plugins-vorbis-0.8.10  0 kB
[ebuild  N    ] media-plugins/gst-plugins-alsa-0.8.10  0 kB
[ebuild  N    ] media-plugins/gst-plugins-esd-0.8.10  0 kB
[ebuild  N    ] media-plugins/gst-plugins-ogg-0.8.10  0 kB
[ebuild  N    ] media-libs/libid3tag-0.15.1b  -debug 0 kB
[ebuild  N    ] media-plugins/gst-plugins-mad-0.8.10  0 kB
[ebuild  N    ] media-plugins/gst-plugins-cdparanoia-0.8.10  0 kB

Total size of downloads: 30,307 kB
bedazzled@bedazzled ~ $