HN profile link? Do people take this seriously?

Some YC companies definitely do. I'd guess that most startups do to an extent.

I think if anything frequent use of HN would reflect poorly on one's productivity.

The same could be said for someone who says "I read books all the time." You could look at it as someone being unproductive (hey if you're reading a book, you're probably not working!) or you could look at it as someone educating themselves.

I've learned a great deal by reading Hacker News.

I've found that printing to PDF on OS X produces documents that look great.

(Unlike, say, Firefox on Linux, it doesn't add header or footers, the text looks great, and in general doesn't look terrible at all.)

The headers and footers are optional. In my Linux Firefox, if I go to the File menu, select the Print option, go to the "Options" tab, there's a whole "Header and Footer" section where you can set them to whatever you want, including "--blank--".

Details of this print dialog might, of course, depend on your GNOME version, your distribution, and the time of month, like everything on Linux.

Now the quality of the text is a separate issue; I haven't actually done any printing from a web browser on Linux in a few years, so I have no idea what that looks like nowadays.

The main problem I have is links. The printing to PDF doesn't care about <a> links. It will linkify anything that looks like a URL or an email address, but that means that I have to have JS put the url in, plus it's ugly to have the urls there at all.

Not sure I understood you correctly, but have you tried using css?

  <style type="text/css" media="print">
    a:link, a:visited {
      color: black;
      text-decoration: none;
    }

    a:link:after, a:visited:after {
      content: " (" attr(href) ") ";
    }
  </style>

Wow. It does? That sucks.

As far as links go, I already treat the resume like a print document; all the URLs are written out explicitly, have their own lines where appropriate. (I guess that's why I haven't run into the problem yet.)