The rad counter is a good idea, but it seems like it could potentially be a little redundant since you would sort of be able to tell by the immediate drop in health points anyways, depending upon how the radiation would affect the player character.
IMO, instead of having a steady drop in health as soon as you enter a radiated area (for example, one health point is lost immediately for every second of exposure; under this system the geiger counter would be redundant), it would be better (if possible) to make it similar to poisoning where you would experience delayed health effects long after your exposure to the radiation, which is more realistic anyways, since in the real world you usually don't start feeling the effects of radiation until after you've already gotten a heavy dose.
You could have a "rad exposure meter" as a part of the interface (similar to a health meter) which measures your overall, cumulative exposure level; it would increase as you are exposed to varying levels of radiation, and would then gradually reduce over time once you leave the irradiated areas. As the "rad meter" reduces, you would lose a corresponding amount of health.
Delaying the health loss has lots of different plusses and minuses, the main drawback being that it would really suck to walk into a radiated area, receive a lethal dose but not know it, and then suddenly keel over dead a few hours later and have to reload and lose all the gameplay you had during the "waiting for death" period. However, the inclusion of the geiger counter/rad meter would offset this (since you'd know it was coming, and the health wouldn't be lost all at once), combined with some wise gameplay and a couple of health packs. Also, extremely high rad level areas could still continue to provide immediate health loss so you don't stay there too long.
You could also have some cool sound effects so that the geiger counter starts making the telltale "clicks" whenever you approach highly irradiated items or areas. I even like the name "Radboy2000" too.
Morte from Planescape: Torment is one of my all-time favorite NPC's.
As for the job application, that's a great idea, you could be my assistant once they hire us.
