Without going into the argue of the importance of PR I'd like to offer a very simple yet powerful way to get backlinks from very high PR sites (PR5 and above!) and from relevant content to your site!
No, its not link baiting (although thats a good way to go if you know how), no spamming or other shady methods.
Let me start from a basic question "whats the hardest thing for a blogger?", the answer is simple - creating frequently very high quality posts. And it doesn't matter if its a beginner blogger or a veteran, it doesn't matter if its a blogger with PR0 or PR8 blog, they all "fighting" hard to produce their quality content.
Sounds obvious isn't it? So why MOST of you never did it?
Why so many are doing comment spamming, profile link building while so few doing guest post writing?
I think many won't try guest posting cause of "stage fear":
"Why would a successful blogger like my post and will put it on his blog?"
I'll tell you why - cause you can think differently from the blogger and your content can be something fresh for his readers, and you will give him the opportunity to "rest" a bit.
I can't imagine a blogger who will refuse to excellent content.
Now, the trick is to create such a good post that a blogger won't be able to refuse, that will require you to make a research about topics that would interest your target blog readers and are not already there. After you choose a topic, with the right research you can write a post which is fresh, interesting and appealing enough for the blogger.
Yes, it takes time to write something like that, but its value is so much more than all those other shady methods, and you get in content backlink from very high PR blogs.
After being "a guest" for a long time and getting unbelievable results I understood the great win-win situation. I believe in that method of link building so much that I decided to start a new project in which I converted one of my PR6 sites into a blog that is based ONLY on guest posts.
How to actually do it?
All you need to do is (scrapebox can be a great help, but its also possible manually) find blogs on your niche, or blogs that are multiniche, sort them by PR and:
1. Research the first on the list
2. Write a great post for it
3. Contact the blogger and send him the post
4. Do the same for all quality blogs you find
Btw, if you do get a negative reply from a blogger, check if you can convert the post easily so it will fit a different blogger, if not use it for your own site or submit it to an article directory - hmmm... did I mention win-win?