[kloc]

While searching for a pdf file, I hardly find the pdf through the top results. The top results are often kind off pdf, ebook search engines themselves and they clearly appear on top by gaming Google. I hope this gets fixed too.

[Matt_Cutts]

If you know it's a pdf that you're looking for, you can add filetype:pdf to your query.

[RyanHolliday]

This is great for HN readers. For most people using Google, not so much, I think.