nkf stands for "Network Kanji Filter," and it's a program used to
convert between various encodings used for Japanese character sets. It
handles ISO-2022-JP, Shift_JIS, EUC-JP, UTF-8, and some variants of the
above (such as the Microsoft version of Shift_JIS). As well, it can do
a limited amount of MIME decoding. It also can try to guess the input
encoding so that you don't have to specify it.

Homepage:
http://osdn.jp/projects/nkf/
