Man pages belonging to programs are usually distributed together with those programs. Therefore, the Linux man-pages distribution mainly contains the pages for system calls and library routines, special devices, and file formats. However, it also contains documentation for a number of programs, in cases where the authors or maintainers of the program do not distribute man pages themselves.
The Linux man pages are maintained by Michael Kerrisk. Corrections and additions are welcome. The page undocumented (3)contains a list of routines present in glibc for which no man page is available yet.
For Czech translations, see ftp://ftp.linux.cz/pub/linux/localization/czman/.
For Chinese translations, see http://cmpp.linuxforum.net/.
For a first start with the Danish translations, see http://www.sslug.dk/locale/man-sider/. (It seems this project is dead - there has been no progress the past few years.)
For Dutch translations, see ftp://ftp.nl.linux.org/pub/DOC-NL/manpages-nl/manpages-nl-0.13.3.tar.gz and http://nl.linux.org/doc/manpages.php.
For Finnish translations, see Project Finnish man pages.
For French translations, see manpagesfr.free.fr and http://manpagesfr.free.fr/download/man-fr-2.39.0.tar.bz2. Additional pages live at http://www.delafond.org/traducmanfr/.
For German translations, see http://www.infodrom.org/projects/manpages-de/.
For Italian translations, see www.pluto.it or ftp.pluto.it.
For Japanese translations, see http://www.linux.or.jp/JM/download.html. See also the JM home page.
For Korean translations, see the above local copy (an rpm file). These are Hangul manpages maintained by Chu-yeon Park.
For Polish translations, see http://ptm.linux.pl/.
For Brazilian Portuguese translations, see http://ldp-br.conectiva.com.br/projetos/man-pages/.
For Romanian translations, see http://www.rolix.org/man/arhiva/.
For Russian translations, see http://www.linuxshare.ru/projects/trans/mans.html.
For Spanish translations, see http://ditec.um.es/~piernas/manpages-es/.