Do you often have 83 open tabs on your browser? Can't refind the one you want? [RAISES HAND] Try out Vivaldi, a new browser with power-user features for managing tab chaos.
For example, if you've got a cluster of tabs all on the same subject matter, you can cluster them together into "stack".
Or there's my favorite feature — a "quick command" box. You launch it with a single keypress (customizable) and you can relocate an open tab by typing in a keyword. It is so speedy and accurate that I'm already using it about once a minute. Seriously, it is crazily useful when you have a zillion tabs open. After only an hour or two with this thing I can tell it's going to become my main browser.
Many of the people who created Vivaldi were the ones originally behind Opera, a browser that had many similar features, and was thus much beloved by power-users. But Opera got rebuilt a while ago, and the developers dropped their custom rendering engine in favor of WebKit; during this transition, they also dropped many of those features, much to the displeasure of the fan base. Vivaldi is an attempt to win over those power-users.
There are other features some folks might enjoy (though I don't use 'em myself), such as a "notes" panel, an integrated email reader, contacts list, etc.
Possibly more intriguing are these features, described nicely in an Ars Technica writeup:
Perhaps the most notable new feature in the second technical preview is what Vivaldi calls "spatial navigation." Instead of reaching for your mouse, spatial navigation lets you click links by pressing the shift key and the arrow keys. You'll see a blue highlight surround each link and you can quickly jump to the link you want without taking your hands off the keyboard. In practice, it's just like tabbing through links, but this method allows you to move much faster since you don't have to go in order.
The last item of note in the latest version is something we expect to see other browsers copying soon: fast-forward and rewind buttons. Fast forward and rewind take a minute to wrap your head around, but once you do they become fantastically useful, especially rewind. Rewind backs you up to the first page you visited at a particular domain. So if you come to Ars to read this review but then clicked around, read a few other articles, and then want to get back to the Vivaldi download link in this piece, you would just hit rewind. Now you're instantly back to the first page you started on.
Fast-forward is a little more unpredictable, but it's still an interesting idea. It attempts to, according to the Vivaldi docs, "jump to the most natural next page" (for example, the second page of search results or the next page in a forum thread).
Given that our infograzing habits are becoming more and more mobile (and increasingly decoupled from the URL, for ill and for good) it's surprising someone would focus on making a new desktop browser. But I'm glad they did!