Rated 5 out of 5 stars
I second rlinn's review, this add-on can make things so much easier, especially for someone like me who sometimes has like 30 tabs open. ^^ It's on a list I made of add-ons that are absolutely essential for me, in case my profile gets deleted and I have to install them all again (I use so many that when I reinstall them I'm bound to miss some).
This is one of those add-ons that I use so much that it becomes an integral part of my Firefox experience, so if I have to reinstall everything, I eventually notice if I've missed this, because one day I'll command-click a tab and it won't turn blue, and I'm like "…Frig." When that happens to me with an add-on, that's how I know that the add-on has become essential for me.