Rated 5 out of 5 stars
This ranks right up there with AdBlock as one of my add-ons I could not live without. It has completely changed the way I do research on-line and it has sped it up enormously. I used to use temporary bookmark folders to store tabs that I knew I'd be wanting again, just not now, but the problem with that approach is that bookmarks don't disappear from their folders when you load them, which makes them a very poor tool for temporary storage. You end up doubling your workload with all the time you need to spend wasting deleting bookmarks once you're done with them, or sorting through them to file them into *new* temporary folders as the ontology you require inevitably shifts as your research progresses. It was a mess, and trying to use tags for that purpose was even messier.
This is the perfect solution. Really, the Too Many Tabs rows *are* just bookmark folders (literally - they're stored in Unsorted Bookmarks), but they're folders that empty and refill and shift function according to your needs without requiring any particular effort on your part. When you load a tab, it is deleted from its "row." If you want to put it back again, you just send it back, or you can put it in a different "row" -- or, of course, bookmark it for more permanent storage or delete it, just as you can any other tab. It's all the time-wasting deleting and resorting and refiling that this add-on eliminates, and it's incredible how much smoother and faster on-line research -- or even less formal web browsing -- goes with this tool.
Designate one row a "reading list," and you have a place to shove everything you want to read later. Or, if you like a more formal approach to your browsing routine, you could make seven rows, one for each day of the week, name them accordingly, fill them with the websites you like to visit on those days, and there you go - you now have a weekly browsing schedule all set up for you (just remember to put the tabs back for next week once you're finished with them!). There's so much flexibility to this system that it can be used for tons of different functions.
You could even use this as a substitute for Firefox's native bookmarks toolbar if you liked -- it has the advantage that you can choose to only show one row at at a time, yet also easily toggle between rows, making it far more flexible and useful than either the native bookmarks toolbar (is only one row long) or any of the add-on versions, like the Multiple Row Bookmarks Toolbar (takes up too much space at one time), or the various additional custom toolbars (can't be toggled nearly as conveniently).
I couldn't function without this add-on. I'm glad to hear that it's going to work with Firefox 4 because honestly, if it weren't, I'd probably just pass on the upgrade altogether.