AUC TeX contains some support for ease the use of various European character sets. This support is contained in two packages "Keymap Mode" in `min-key.el', which support general remapping of the keyboard, as well as converting between various character set encodings, and "Dead Key Mode" in `ltx-dead.el', which support dead keys for entering accents. Both packages depend on the "Minor Mode Keymap" support in `min-map.el', but at least "Keymap Mode" is otherwise useful even outside AUC TeX.
If you have the necessary software, AUC TeX will also work with some Japanese versions of TeX and Emacs.