This one is good on JR, private rail lines, all subway lines, TOEI busses, and a few other places within roughly the 23 wards of Tokyo. It is Y2,500 for two consecutive days (not much of a deal IMO) and Y3,000 for three consecutive days (possibly a good deal if going to be touring Tokyo a lot).

Here's the detail:

http://www.visitjapan.jp/eng/common/transport_eng.pdf

It's available just from Dec 1, 2011, through January 31, 2012. Note that the map is a bit deceiving as it shows some lines in yellow where the pass is NOT valid. It is Suica-like in that you can use the fare gates when within the area of validity. Can only be bought at Narita and Haneda.