Celebrities and stylists are really jumping on the extreme, never found in nature hair colors. There have been lots of bright pink ( Pink, Katy Perry ) but, blue seems to be gaining popularity.
My only question is if blue hair severely limits your clothing selection? I mean if you already have clown hair you would have to be extremely cautious not to wear clashing colors or a clown outfit.
There were some girls with bluish hair when I was growing up but, it just meant their parents used too much chlorine in their swimming pools :)