Tokyo Museums - Grutt Pass 2005 is a multi-museum admission ticket for 46 facilities including museums, art museums, zoos and aquariums in Tokyo.
The pass is 2,000 yen and is valid for two months from the first admission.

Although the pass covers free admission to the permanent exhibitions (and even some of the temporary exhibitions) of many museums and galleries, it only offers a discount on some others - a notable example is the Mori Museum which I believe is offering a measly 300 yen off it's current hefty 1,500 admission charge.

For more details and where to get it:
http://www.museum.or.jp/grutt2005/about-e.html (EDIT: link dead - please see post #11)

Does anybody know what the symbol next to the Mori observation deck means?

As so many of the facilities are usually about 600 yen, I guess you'd need to visit at least 4 places for the cost to be viable - but that's easy enough on a visit to Ueno, or even Odaiba, on a rainy day - Dinosaur FACTory anyone??? http://dinosaurfactory.jp/en/index.htm

A list of the participating buildings are here: http://www.museum.or.jp/grutt2005/list-e.html - watch out for the places shaded in yellow as they just offer discounts.

The blurb mentions aquariums (plural) but the only one seems to be the distant Tokyo Sea Life Park. Again, I don't know what the symbol next to it means.

If only there was something similar for Kyoto too....

APART FROM THE EDO TOKYO MUSEUM IN RYOGOKU (it gets a big thumbs up from a lot of people), DOES ANYBODY HAVE ANY PERSONAL RECOMMENDATIONS?