I think it's really cool to get a latte that has some type of artistic design on the top. I've only gotten a drink like this once, but it really was neat to watch the barista take the extra few seconds to make a cool pattern on the top of my latte. It earned her a bigger tip, that's for sure.
While I will never be doing this type of thing at home (I don't make lattes at home and am not nearly this artistic), I think it's interesting to see the creativity that can turn coffee into a temporary art form. This video will show you how to create many of the more common designs.