My family is Jewish. And though we're not religious, my dad still tries to take it pretty seriously. It's against the Jewish religion to get tattoos, and if you get one you can't be buried in a Jewish cemetery. That's my dad's main argument against me having tattoos. But personally, being only 20 years old and considering myself agnostic, I'm not too concerned with where I'll be buried right now.
I have heard that a Jewish person with tattoos could still be buried in a Jewish cemetery though, but they have to peel off the tattooed part of the skin.
And interestingly enough, there are many young Jewish people, especially in Israel, who are getting their grandparent's/great-grandparent's concentration camp numbers tattooed in order to never forget the Holocaust. This has had mixed reactions. Some say it's good that the younger generations remember the Holocaust and their relatives who either survived or passed away. But others still want to stick to the traditional Jewish values and see getting the number tattooed as demeaning and a way to strip a person of his or her humanity. But if you change the meaning for yourself and see it as a symbol of strength, it can be a great commemoration.