Free Museum days in Paris, a few of my favorites

I love museums, and fortunately for me, I currently live in a city with some of the best museums in the world.  Other than the big names of the Louvre, Centre Pompidou, and Musee D'Orsay, there are many lesser known ones that are equally worth going to. 
Since I am no longer in the "under 26" age group, where entries to many museums are free, and since I am also too cheap to pay, I take advantage of the Free museum days.

One of my newly discovered place is the "Jeu de Paume".  It's a gallery right next to the Jardin des Tuileries that holds photography exhibitions that changes every few months.  It consists of three levels, usually with a different exhibition on each level.  They recently just concluded an excellent and compelling exhibition on the works of the now jailed Chinese activist/photographer Ai Wei Wei. 

Free when?

Only for studetns and those under 26 ! The last Tuesday of every month from 17h to 21h.  I would advise going before 19h to avoid a long line.
http://www.jeudepaume.org/

Another place that I've frequented is the Maison Europeene de la Photographie. It is located in a side-street near the metro "St. Paul".  It houses collections of contemporary photographic art as well as temporary photography exhibitions that changes frequently.  It's a must go for any photography or contemporary art fans!

Free when?

Every Wednesday evening from 17h to 20h.
http://www.mep-fr.org/us/default.htm

Musee des arts et Metiers has a collection of "stuff" and objects from science, engineering, transportation, communication, energy, etc.  They are displayed in a chronological order.  The museum is fun for kids and especially science geeks!

Free when?

The first Sunday of every month, and every Thursday from 18h to 21h.
http://www.arts-et-metiers.net/musee.php?P=228

The following is a list of museums that are free the First Sunday of every month (courtesy of Parisinfo.com)

Musée national d'art moderne - Centre Pompidou – 4^th

Musée de l'Assistance Publique - Hôpitaux de Paris – 5^th

Musée national des Arts asiatiques Guimet – 16^th

Musée de la Chasse et de la Nature – 3^th

Musée national Eugène Delacroix – 6^th

Musée Gustave Moreau - 9^th

Musée national Ernest Hebert

Musée national Jean-Jacques Henner – 17^th

Musée du Louvre – 1^st

Musée national du Moyen Âge - Thermes de Cluny – 5^th

Musée national de l'Orangerie – 1^st

Musée d'Orsay – 7^th

Musée national Picasso – 3^rd

Cité de l'Architecture et du Patrimoine – 16^th

Cité nationale de l’histoire de l’immigration – 12^th

Musée du Quai Branly – 7^th

Musée Rodin – 7^th