Check this for ISOs: http://en.wikipedia.org/wiki/Film_speed#Di..._exposure_index
Regarding "full" stop ISOs they are differently implemented on cameras.
The figure below may give you some idea.
There are considerable choices regarding ISO on digital cameras. One limitation is that the sensor cell can hold a certain number of electrons, this is called full well capacity. FWC is the limit for low ISO. The issue is quite complex. Basically, exposure should be to the right, as near FWC as possible, for the least noise and highest DR. The tonality of the image is created during postprocessing by camera CPU (JPEG) or computer (RAW).
i believe the "native/true" ISOs are 160, 320, 640, 1250, 2500,...
i'm still curious why Canon and Nikon have the same "native" ISOs
similarly curious why you must use the full range of settings to select the "native" ISOs and when you select full stop ISOs you get 100, 200, 400, 800, ...
how much difference is there really? is the noise at ISO 160 really the same as ISO 100? 640 the same as 400?