maybe I'm in left filed here but... I'm willing to suspect that the reason why your sites don't get any traffic is because they don't make much sense. From the Astrology Blog From the Technology Blog I am in no way making fun of your English but I would recommend having a native English speaker look over your content before posting it, or use your native language.
I believe PR is part of you domain authority score, it is just one of the many attributes Google uses to rank your website. Another mis-conception I see is that people need to quit thinking of SEO for their "website", please think of your website as a collection of "webpages" that will need to each rank for the most relevant terms deemed by Google. -D
If you have PR, you can sell links or have a link exchange with more popular sites (sometimes PR does not matter).