You could use a helper application to read .pdf files. Preview comes with Mac OS X, and it can read .pdf files.

Unfortunately, this doesn't help. True, using a helper app for EXISTING PDF files DOES work. This problem occurs when converting non-PDF sources INTO PDF.. Note that this works properly in Safari but NOT Firefox. It appears to be a Firefox problem when converting to PDF.

You could print the page to a .pdf file. Set that up in File > Print > PDF (button). I just tried that. It works for me.

Unfortunately, it is the "print to pdf" that isn't working for me. I am aware that it works for some people and not others. But it seems that this only happens with FireFox.

I found that you can also use File > Print > Preview, which will open the page in Preview. You can save the file as PDF from Preview.

I've had this problem of crashing when printing webpages to PDF in Firefox off and on with various releases of Firefox and OS X for years now. Sometimes it's intermittent, only happens printing certain pages, sometimes it's consistent, crashes on any web page, but it eventually goes away with a new release of FF. Only to return in a future release...

Print to PDF was working fine with FF 14.0.1 and OS X 10.7.x, but since I upgraded to 10.8 it consistently crashes on every attempt to print any webpage to a PDF file, on both my iMac and my MacBook Pro. By now the Mozilla crash reporter has sent a whole bunch of crashes to Mozilla from both my Macs. Awaiting a fix. Again.

Additional info: I've switched to Safari to avoid this problem, and guess what - printing web pages to PDF files crashes Safari 6.0 too! The crash seems to be happening in the HP printer drivers, so I suspect this problem has been triggered by the recent update to HP printer drivers rather than OS X 10.8 itself or Firefox.

Resolution (24 Aug 2012): This problem was resolved by the installation of OS X 10.8.1 and the HP printer drivers v2.11 released today. Both FF 14.0.1 and Safari 6.0 can now print to PDF without incident.