Well... I am! Most extensions would work with Firefox 1.0 if authors declared maxVersion as 1.0. What can we do? Well, we can repack them using shell script and increase maxVersion to 1.0.
This script will by default increase maxVersion to 1.0, but you can also give any maxVersion as second parameter (for example 1.1 when it's available). First parameter is extension.xpi file. That file will be replaced with new file which has new extension version (I add +ver1fix to it). It shouldn't break extension update feature (if authors decide to fix maxVersion and increase version of extension).
This script comes without any warranty. If might break your Firefox if you try to install extension which really doesn't work (and I had few cases like that). On the other hand, it might save your day.
Update: fixed download link, again...