New museum discount scheme at four museums at or near Chaillot: Musee de l'Architecture, Musee de l'Art Moderne de la Ville de Paris, Palais de Tokyo, Musee du Quai Branly. Download or pick up a free pass. Good for five consecutive days, you pay full tarif for the first museum, reduced admission for the next two, and admission to the fourth museum is free.
http://www.lacollinedesmusees.com/?lang=en
Also, Saturday 16 May is the
Nuit des Musees -- most museums free from 6pm-midnight or later.
The English link doesn't seem to be in English, but it says that the program for the event will be in Friday's edition of Metro, the free daily newspaper.