When pg implements proper hyperlinking that doesn't clutter up my text with an ugly URL, I'll stop using a shortener. I understand the positives and negatives of using a shortener, but the positive impact on readability seems to outweigh the negatives when I'm confronted with an ugly link longer than the text I use to introduce it. Sorry if that offends you.
I should have noted that my link was a PDF, though. My apologies for that oversight.
Actual URL is http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.90.... and that is a direct link to a PDF.