Personally, I don't have any opinions about tattoos.
As an employer, I don't think they should be visible while you're working. I consider them to be unprofessional when visible while working (i.e. representing your employer, not representing just yourself)... but I'm actually not sure why I think that way. Most employers feel this way, especially in professions that don't involve French fries. They would need to be covered with clothing or camouflage makeup at all times during work. That's something to think about if your considering where to put it.