We have no idea if the domain you're talking about is generic and no idea if the other person has a trademark. What you want to do is a very common practice and in many cases it's perfectly fine. In some cases, though, you might find your self getting hit with a lawsuit or a WIPO case.
Without knowing the specific name and the person who owns it, then it's hard to say.
If he has a trademark, then you shouldn't do it.
Check it here:
http://tess.uspto.gov/