Safari is the only browser which allows you to open pdf files inline. All other Mac based browsers force you to download the pdf.
This greatly upsets me
How many times have you clicked on a pdf link without realising it? Before you know it Preview or Acrobat is loading up in the background and you’re going to have to switch windows in order to view the desired content.
Being forced to relinquish control over your actions because of your browsers’ shortcomings is simply not on.
There are no Acrobat or Preview add-ons for Firefox, Camino or Opera to come to your rescue. This is where PDF Browser Plugin saves the day. Download and drop the PDF Browser Plugin.app file into your Library > Internet Plug-ins folder and relaunch your browser. Navigate to a PDF file and click on it.
Ahhh! It begins to download again
This is because this plugin doesn’t work on Intel Macs. But there is a solution. You can switch your browser to open under Rosetta to rectify the situation.
Rosetta is basically a translator which allows native PPC based applications to run under Intel Macs.
In order to open your browser using Rosetta, you must click on the ‘Get Info’ option when you right click on your browser.app folder within Applications. Simply tick the box which says Rosetta. And there you have it! You can open PDF documents inline with your browser.
If you use Firefox or Flock you can control PDF files within your browser even further. PDF Download is a very nice plugin which prompts you when you’re about to open a PDF file. It asks you whether you want to download, open in the browser, open using HTML view, or cancel.
All in all I have to say that I’m disappointed with the handling of PDFs on Mac based browsers. Safari being the only browser to interact without any user configuration is a real let down. Mozilla and Opera need to get in gear and improve their handling of PDFs. I’m sure better PDF handling is a feature request they have seen before..
iUseThis 



