PageRank is not about voting for websites or vouching for them. An incorrect metaphor is being propagated to the point where Google's own employees are confused as to what PageRank is supposed to be about, as per Larry Page and Sergey Brin's Anatomy of a Search Engine paper.

Google's founders conceived of PageRank as the likelihood that a user will visit a particular page on the Internet. The more likely you are to visit, the greater the PageRank. Yahoo.com is the most popular site on the web. Its PageRank? 10 Points of Green Fairy Dust out of 10.   

As the Is Link Juice Limited post and comments show, PageRank is calculated by considering the number (probably since modified to also consider the quality and relevancy) of incoming links to a page with some consideration for the number of outgoing links. Now, it is only logical that if there is a link somewhere on a page to another page, there is a certain likelihood that someone will visit that page. That page now has a certain PageRank.

When you put nofollow on a link to prevent it "passing PageRank" you're misunderstanding what PageRank is. The very fact of having created the link means you've increased the likelihood, or PageRank, that a certain page will be visited. The idea of a nofollow is a non sequitur. If you don't want people to follow a path from your page to another page, don't create that path. Don't give a link.

(On a related note, I read somewhere that mentions of a site, even without there being a link to it, will be counted in its favour as per a recent Google algorithm. If the webmaster didn't link to the site, you're probably missing the point by calculating the mention as a plus. The flip side is that any mention increases awareness and curiosity, so some determined people may still try to find the site. It's a factor that can cut both ways and you should give it careful consideration before integrating it into your algorithms.)

Finally, I recall there being a whole debate about whether Click Here anchor text was good. Considering Marketing Sherpa found that it increased CTR, wouldn't you agree that it's good anchor text and should pass even more PageRank than less action-oriented links? 

(Some further reading: my friend Ben Yoskovitch of Standout Jobs has a great post on the 5 types of links.  And I'm going to repeat my above link to Brin and Page's paper: click here to understand PageRank. Third, if you like my writing on technical stuff like this, then click here to read some SEO FAQ.

P.S. By the way, if I am wrong on any material points above (Perhaps I'm the one who's misunderstood PR? Certainly could be! Wouldn't that be ironic? hehe...), share your comments below.