You can surgically remove the foreign language support files included in rpm packages by deleting all the directories in /usr/share/locale/ except
the en_US directory. Of course, installing any new package or updating any package that places files there will bring them back. On my system, doing that would free up about 402MB of disk space.
BASH:~/-> du -hs /usr/share/locale
BASH:~/-> du -hs /usr/share/locale/en_US
Doing "yum clean all" is not much of a solution, as yum will only have to re-create most, or all, wiped files the very next time you use yum. Though, if you ever used "yum search", those filelists.db files are huge, and avoiding the use of "yum search" again will keep those at bay. As stevea already suggested, removing packages you don't either need or use can pare off a lot of unneeded bloat.
BASH:~/-> ll /var/cache/yum/x86_64/16/fedora/4497b3b08a1e8698de02474c664f6c513a5c4d83370543228f31523234e6874a-filelists.sqlite
-rw-r--r--. 1 root root 121817088 Mar 28 19:15 /var/cache/yum/x86_64/16/fedora/4497b3b08a1e8698de02474c664f6c513a5c4d83370543228f31523234e6874a-filelists.sqlite
Edit: Note also, removing those locale directories could provoke yum into spitting out a lot of warning messages when yum does a "yum check".