If your work is good, and could be relevant to a position in some way it's worth including. I enjoy seeing people who like to sketch, photograph, sculpt, paint, etc in their free time.
If your work is amateur, or could potentially be viewed as "inappropriate" (you'd be surprised at the number of portfolios I've seen with stuff bordering on porn) then I would leave it out. I just reviewed a portfolio last week with a guy who had his photo section with one picture of his girlfriends boob in his mouth. I respect your right to "artistic" expression but you should carefully consider what your "Extra" content might reveal about your personality in a negative light.