How do you answer this interview question?

In a recent job interview, I was asked this stress question "What skills do you think you lack for this position?" This question caught me unprepared. So I said something that obviously didn't impress the interviewer. After the interview, I did a little research on the Net and got some ideas as how to answer this kind of questions properly (such as this sample answer). However, I would still like to see how you guys would handle this question in an interview. By the way, I was applying for a Web-based application development position with a software company.

Thanks