It's helpful to have multiple FF profiles as you experiment with plugins and try out various options. I find it useful to have one profile where I disable images (cutting down distrations and have perceived faster page load times). You may have noticed that FF normally doesn't allow to run multiple profiles at the same time.
This can be averted using the following command:
firefox -P Default -no-remote
More details are here:
http://crunchbanglinux.org/forums/topic/2518/firefox-profiles-for-plugin-management/
