One of the better starting pages with frequent updates and daily status tables is:
http://en.wikipedia.org/wiki/Timeline_of_the_Fukushima_nuclear_accidents

New status page, English

Near real-time sensor data could be found through the following pages:
http://www.tepco.co.jp/en/nu/monitoring/index-e.html (English)
http://www.tepco.co.jp/nu/monitoring/ (Japanese)

The pages show information from both Fukushima Daiichi (Fukushima 1)
and Fukushima Daini (Fukushima 2).

If you want to compare the Japanese pages, even if you cannot read Japanese, the fourth symbol indicates 1 (Dai-Ichi) or 2 (Dai-Ni) and is intuitively intelligible:

福島第一  =  Fuku shima Dai ichi (1)
福島第二  =  Fuku shima Dai ni (2)

The actual data tables have the following columns:

Time | Sensor | Gamma Radiation | Neutron Radiation | Wind Direction | Wind Speed

The sensor identified by two kanji symbols is the outer sensor at the west gate. The other sensor, identified by 5 kanji symbols, is inside the compound, to the north of the service building.

西門  =  West Gate
事務本館北  =  North of main service building

I wish that everybody follow the Japanese example and publish such data in real-time for all dangerous accidents.

Please add a comment if you have additional or better information. I will improve this article, whenever new information becomes available.