Vivaldi is a new browser from a team lead by Jon S. von Tetzchner, the co-founder of Opera.
The end result is streamlined and straightforward to use. Browser tabs at the top of the page, address and search bar below, a menu button top-left points to a few useful options (File > Import Data can import your bookmarks, passwords, history, and search engines from IE, Opera and Firefox).
A tabbed panel on the left gives access to various extras. A Notes section allows you to take text notes and screen shots, and add tags to any site. There are Downloads, Bookmarks and Contacts panels, too, as well as one for "Vivaldi Mail" (although a message explains this "is not ready") and a web panel option, which lets you pin frequently accessed web sites, feeds and other resources for easy access alongside the main browser window.
The Speed Dials page doesn't just display static thumbnails of your favourite sites. You can organise them by interest, context, add folders, and more.
Open too many sites and Vivaldi offers a new way to restore order. Dragging one tab over another creates a Tab Stack, where a single tab represents multiple sites. This works much like a group of buttons on the Windows taskbar: hover your mouse over the tab, thumbnails appear for each of the sites it represents, and you simply click the one you need.
There's also very good keyboard support via "Quick Commands". Press Ctrl+Q at any point and a menu appears listing all your open tabs and most important commands. Select whatever you want directly from the list, or press the listed hotkey (Ctrl+H for Notes).
Vivaldi's customisability and flexibility is joined by genuinely innovative features such as tab stacks and web panels to make it a genuine alternative browser for the power user.