Google toolbar is Windows IE only.
I used to have to boot up my PC to check page rank but then someone posted this link.
http://www.freelance-help.com/google.../page-rank.php
There was a Google bar for Mozilla on Mozilla's development page, not made by Google, that did lots of what the real Google bar did except page rank. I'm not sure if they have updated it or not but last time I checked it was broken with the newer builds.