Sidebery is fantastic, but I do have to mention, that it had bugs in the past. It sometimes put all my tabs into the same group, so that I had to sort them anew, and sometimes it crashed, so that Firefox reloaded it and redisplayed the sidebar.
Lately I have not had any such issues with it.
I've had this happen once a few weeks ago, and enabled auto-snapshots, so I think if it happens again I can just restore the most recent one.
Also, in the past I've had Firefox crash in some weird way where it lost all my tabs, so I hope I'm safe from that too. (Tho it hasn't happened in a long while.)
