Hi, I have noticed on here and other places. New domains (under 6 months) that are genuine PR 2, 3 and 4, yet they either have no site on that domain or the site has very very and low PR back links. How is that achieved?
There are many ways people are doing it. 1. The domains earlier had content and it was a genuine PR, domain owner didn't renew the domain name and hence a 'dead' site still carries the PR. 2. People can redirect their site to a high PR domain for some time and get PR on their domain.
In addition I would say that the green Pagerank on you Toolbar is just the graphical representation of the earlier record of a site! So you will find the change immediately after the Google PR updates. But it is interesting that you found a domain with PR4 though there is no site available! Can you give me those links?
google only updates the pr bar every 3-4 months, chances are it just hasn't been updated since the site closed.