Day six of rolling blackouts and reduced train service.  It seems that 
electricity usage will not be too high today this weekend.  Many rail 
companies will keep all sections open.

The following rail companies plan to keep all sections open on March 19:

Haneda Monorail
Keikyu
Tokyu
Odakyu
Tobu
Keisei

Toei Subway

The following rail companies plan to keep all sections open, with minor 
exceptions:

Tokyo Metro
(Fukutoshin Line north of Ikebukuro closed, use Yurakucho Line instead)

Keio
(Branches to Fuchu racetrack and Tama zoological park closed)

Seibu
(Underground connection between Kotake-Mukaihara to Nerima closed.
No through service to subway lines.)

Several JR East and JR Central lines will stay closed.  With the 
exception of Sagami Line and lines in the Tohoku area devastated by the 
quake, they are mostly local lines.

Details on scheduled section closures here:
http://www46.atwiki.jp/earthquakeinfo_en/pages/15.html

Narita Express will not run but JR East says that all rapid/local runs
to Narita Airport will run.

Keisei Skyliner is running.

JR East has announced recovery plans for the Tohoku area:
http://www.jreast.co.jp/pdf/saikaijoukyou.pdf (Japanese, shows what 
lines are already open or will open soon)