I actually just got done touching up the dip dye on my hair-- it's currently Manic Panic in Rockabilly Blue and it looks great, I think. The biggest worry I had with it was the bleaching-- I was terrified that I was going to ruin my hair. I only bleached what I wouldn't mind getting cut off in case something terrible was to happen with it, and it's been about 3 weeks now since I've bleached and I really haven't noticed a difference in the health of my hair!
I bleached from a medium brown to a really light, silvery blonde, so I did a loooot of processing! In order to make the color stay, you really have to process your hair first, or else it won't be able to "grab" on and will all rinse out. If you do color your hair, read this.
It's full of awesome tips.
I would add a picture, but you can't really see the blue unless I'm in natural light. I'll come back and add!