So far, my only mac grievance has been the fact that the pdf’s from arXiv.org, don’t behave properly in Firefox 3 (due to bad code at arXiv, it seems).
Anyways, this prompted me to finally get geeking with Greasemonkey, an übercool Firefox extension that lets you run your own javascript on any site of your choosing. Ten minutes with the excellent tutorial at diveintogreasemonkey, and ten more minutes of interactive trial and error from the Firebug js-console and voila: a quick hack ready to go to userscripts.org.