Here is a gorgeous polish that needs little introduction... the fabulous Nfu Oh 65, a bright sky blue holographic.
I also snapped a picture of the holo effect (indoors) with and without top coat (Seche Vite). The results here look fairly dramatic. I will say the holographic effect improved after the top coat dried, as this was seconds after application. It seems that without top coat is definitely the best way to preserve the effect, but I can't quite bring myself to do that. :)
With top coat --------------------- Without top coat