That's a tough question, because it requires subjective judgement, and setting boundaries to define what is moral and ethical, right and wrong. My world has an abundance of shades of gray.
From my subjective POV, the oppurtunists that try to profit from a name that exploits others tragedy( ie 911), misfortune, sorrow, pain, weakness, and/or socio-economic disadvantage in any area, be it porn, religion, health or social reform are wired differently than I am.
How I define what is off-limits for me, therefore, does not easily break down into subject or content catagories.
For instance, a social organization or religious institution that preys on the elderly, although not as repugnant as a filmmaker manipulating children to perform sexual acts, to my way of thinking, is in the same category and equally taboo.
Unless very literal, it is also difficult to label a domain name as being on or off limits. In most cases, it is how a name is used and not the content of the name itself that is the problem. To wit, "free medicine" could be used in a very immoral way, and "kiddieflix" could be a very healthy and nourishing site for children.
Also, in my own life, I have seen my perspective and values shift. When I was young and raising a family, I took a much harder stand against porn and what I perceived as moral deviance. Looking back, I see my values, than, as being consistant w/ the instincts and protective nature of being a parent. Today I view porn and other exotic sexual activity as not being such a large issue, see it more as one of life's passages for many people. Larger issues for me today concern issues of justice, fairness, and equality, and I generally have more acceptence and compassion for people and this human condition that we all find ourselves in.
Happy Holidays Everyone!