[throwaway914]

Sidebery is wonderful, but the real gem is Tab Stash. Lets me organize tabs into topic-related groups, with the added bonus that not all of these are "living" tabs. Some are archived/hibernated. By default, live tabs are in an unorganized/unnamed group. The only issue I had was I couldn't tell which tab was playing audio. Tab Stash doesn't have indicators for this, so I installed the Sound Control extension to list tabs playing audio and switch to them.

I got: vertical tabs, tab grouping by topic/label, tab archival (low memory use)

[Sujeto]

In grasshopper you can organize through tags, and colors, which create profiles mapped to urls, so they also apply for instance if you are in History view. The profile can be set to match the root, or the exact url. You can also filter different kinds of tabs, like unloaded, or playing. There's also a button that appears when a tab is playing, to go back to that tab (focus it).

[dizhn]

I use Simple Tab Groups which has similar features. It works great and its autosave also saved my open tabs a few times.