The no follow attribute means "don't follow". It's not about PR per say. So if you put no-follow attributes on every hyperlink linking to your contact page, your contact page will not be indexed...unless someone else is linking to it. I don't know why there is so much concern about the no-follow attribute. I would never use it to manipulate rankings: a total guess at best and there is no way to accurately judge the effectiveness of such manipulation as the PR bar is always out of date, Google used hundreds of factors to rank a page, and search results naturally shuffle around all on their own whether you do anything or not.

I only use it to block a spider from indexing a page.

Google encourages you to use it on paid links to make their life easier, not yours.