An important part of my work is reading scientific publications, which nowadays all come as online pdf files. Unfortunately, with Gentoo amd64, the Acrobat Reader plugin situation has lately been far from satisfying, with the plugin crashing and pdfs disappearing from the screen regularly. I know that the recommended thing to do is to install a 32bit firefox-bin, which supposedly works more stable with the 32bit Reader. However, from a Gentoo poweruser point of view, that's definitly uncool.
So, what else can we do? Turns out, there is a really nice solution for this problem, as long as you already run KDE and use it to view documents: remove the Reader plugin completely, and just install kde-misc/kpartsplugin. Automatically, after a Firefox restart, your browser can display everything that a KPart is available for. This means, a pdf or ps will get you an embedded viewer just like Okular, and much more... Somebody has been thinking this through a lot, you get buttons "Open in separate application" and "Save as file", and if there are several KPart's available, you can choose one and optionally save that preference. Works great here, and the pdf display is way faster!