What I'm going to describe is not an entirely dramatic change, but one that will get you noticed.
On the TV show Andromeda, Actress Lexa Doig during the later seasons of the series (which has ended), had a wide bright red highlight running down the sides of her hair. And I thought she looked so cool with those highlights. I just loved it. Anyway, I've found some pictures and the links are below, but unfortunately the pictures I found just don't do it justice. But at least you can get the idea.
The nice part about the highlights like that is that you could do a dye job, or (and I'm guessing here, but I'd be willing to bet real money on it) that somewhere in N.Y. or LA there has to be a hair/wig salon that would have this as a ready made extension.as well.
Whether your a brunette, blonde, or redhead this little trick would work quite nicely in my opinion, and definitely get you noticed. Yet still remain tasteful and not look insane. The best of all worlds..
Hope this helps you out. I think it's a great idea. if you should decide to go for it, I'd love to see a picture of how it turned out.