Do you respond to negative reviews?

I want to throw a question out to some of you who are authors. On Zoe Winters' blog, we were talking about reviews and how crazy and mean some readers are, etc. I was going to ask this question on her blog (since there are so many more people following it), but I didn't want to use her blog for my own ramblings. The question is, how many of you actually respond to reviews on Amazon or other places? Does it depend on what the reviewer says or how personal they get with you? I recently...