Status bar icon Rated 5 out of 5 stars
The latest version removed the status icon since there's now an add-ons toolbar in Fx 4. However, anyone still using Fx 3.6 or below can get that status icon back by using version 0.4.7 of MeasureIt. You can get that version at https://addons.mozilla.org/en-us/firefox/addon/measureit/versions/
Cheers and thanks everyone for using MeasureIt!