Here are the outputs from the Geiger Counter in our office in Roppongi 2-Chome, Tokyo:
4 hour reading
24 hour reading
One week reading
The geiger counter in our office is similar to this unit: Craigset.
The units are micro sieverts per hour. See here for an explanation of sieverts: http://en.wikipedia.org/wiki/Sievert.
Kalin Kozhuharov has another counter down the road in Mita. You can check results from his counter here: http://thinrope.net/gamma/.