piatkow - 10:56 pm on Feb 1, 2010 (gmt 0)
I agree with murphsy. The site owner should be the one who can best identify the good authority sites for his niche. The best single thing that I ever did to improve positioning was fix a page that didn't have an h1.
My golden rule has always been to build links for relevance rather than PR. Will the sites I link to add value for my visitors? Will my site add value to those who I ask to link to me? Will the sites that I ask to link to me bring me traffic through the links? Good positioning in the SERPS for key search phrases always seems to have followed.