No backlinks and Higher Google Page Rank?

Question

Many many people are trying hard to get lots of backlinks to get at least Page Rank PR2 (even quality backlinks).

How it is possible that my personal website which I actually have not advertised (apart from this question now ;-)) http://www.nasadowski.com has PR3 ? There is no reason why my website should have this PR.

This is very interesting for me because as a web designer I try to promote my other official business website but it's got lower PR than this personal one.