CTAN has a new package: frletter
A small class for typesetting letters in France; no assumption is made about the language used. It represents a cosmetically modified beletter class, which itself is based on the letter class. Corresponding layout files were contributed on the Lyx Wiki. The authors of the original beletter class are James Kilfiger and Frank Lenaerts. The contributor of frletter is Liviu Andronic.
This package is located at http://tug.ctan.org/tex-archive/macros/latex/contrib/frletter . More information is at http://tug.ctan.org/pkg/frletter (if the package is new it may take a day for that information to appear). We are supported by the TeX Users Group http://www.tug.org . Please join a users group; see http://www.tug.org/usergroups.html .
frletter – Typeset letters in the French style
A small class for typesetting letters in France. No assumption is made about the language in use.
The class represents a small modification of the beletter class, which is itself a modification of the standard LaTeX letter class.