wow! big text to help the visibly insane? you don't even know me, but thanks!
that picture you speak of was photoshopped. That light bar is a Jeep Liberty accessory. No one that I know of has attempoted to install one on a Nitro. It seems like quite a big deal to do and you have to drill holes in the roof to attach it and run the wiring. There is a member in England that has one from a Jeep he had, but I don't think he installed it.
Here is a thread about this and there were diagrams and stuff I remember seeing:
http://www.nitroforumz.com/showthread.php?t=6546&highlight=roof+lights