You do have some control over how the PDF appears in the browser by passing some options in the query string. I was happy to this working, until I realized it does not work in IE8. :(
It works in Chrome 9 and Firefox 3.6, but in IE8 it shows the message "Insert your error message here, if the PDF cannot be displayed."
I haven't yet tested older versions of any of the above browsers, though. But here's the code I have anyway in case it helps anyone. This sets the zoom to 85%, removes scrollbars, toolbars and nav panes. I'll update my post if I do come across something that works in IE as well.
<object width="400" height="500" type="application/pdf" data="/my_pdf.pdf?#zoom=85&scrollbar=0&toolbar=0&navpanes=0">
<p>Insert your error message here, if the PDF cannot be displayed.</p>
</object>