Here is an up-to-date list of High PR Article Directories with DoFollow links for 2012. These article directories have all been checked for PR and Dofollow links verified. You'll notice that PR above 5 is few and far between with article directories and the reason is the amount of spam/duplicate content being submitted.
Article marketing and Guest Blogging has got to be one of the best sources of free traffic and backlinks because you are attaching your links to pages of unique content and keywords. These articles will rank in search engines and if your content is helpful you will gain lifetime followers and customers.
If you want to get the best results from article marketing then it is a good idea to write original articles and posts each time you submit content to directories.
This will give you the highest approval rate and greatest chance of ranking high so you can get real traffic to your pages. You don't want to submit the same article to multiple directories because then you will be diluting your keywords with duplicate content that Google is just going to block anyway.
Add something valuable and people will share your links. If you spam a bunch of paid ads then visitors will just click away and directory owners will trash your articles. So my advice, as an article directory ownerf, is to take the time to write 1 really good article. Write an article that will get people's attention and actually improve the quality of their lives. Make it count or you're wasting your time.