For anyone dealing with French clients or suppliers:
www.economist.com/cities/displayobject.cfm?obj_id=2343734 - French business etiquette from The Economist

For translators and interpreters:
www.iti.org.uk - Institute of Translators and Interpreters website, information about membership
www.iol.org.uk - Institute of Linguists website, information about qualifications and upcoming examinations

For lovers of anything French:
www.institut-francais.org.uk - French culture in London
uk.franceguide.com - To plan your trip to France