While growing up I had my hair every single color I could get my hands on. Purple, Blue, Pink, Black witth blue tints or purple, Neon red, ect... It was fun and I didn't care what others thought, you shouldn't either.
I was the best kid any parent could ever hope for- and I dyed my hair. I tried Kool-Aid, I tried markers during math class, and I tried some purple gunk I bought from a music store that turned my hair green. If you have naturally black hair, I think dark blue would look killer, especially if it was subtle or in thin streaks. It sounds like you want people to be able to notice it right off though, so I would recommend getting something that can wash out first.
i'm no longer a kid, actually i am a mother, and i just recently died my hair purple. no big deal, as long as you don't care what other people think of you, cuz believe me you will get all kinds of comments and funny stares
I think it's cool... I mean, I have a friend whose hair is a different color every month. But, teachers and parents are kind of ticked by it, so it seems...
do what makes you feel good. it's not a permanant thing. my hairdresser once said "you know the difference between a good hair-do and a bad one?" answer: a few weeks! lol