French translation is up there!
If you target bi-lingual regions or want to target broader audience you can keep English language on, allowing the visitors to quickly switch between English and French versions by hitting the links on the top. This way operating in Quebec or Montreal, you can rest assured that your visitors are free to choose their native language, while it'd be worthwhile to enable Spanish approaching running your site in Florida or California.
Needless to say that you can keep on as many languages as you like and make your site really multi-lingual. French, Spanish and Russian can be enabled in no time. Here comes a tricky question:
Q: I have many languages on my site which language the subscribers will be receiving their emails in?
A: The system "assigns" the language at the moment of subscription i.e. if the user subscribed when being on the English version of your site, s/he will be getting emails in English, if they were viewing French version at the moment of subscription - in French and so on.