Opera Neon is a concept browser (web OS) from Opera available for Windows and Mac.
“Opera Neon’s newly developed physics engine is set to breathe life back into the internet. Tabs and other objects respond to you like real objects; they have weight and move in a natural way when dragged, pushed, or even popped.
With video pop-out, split screen mode, a rebuilt omnibox and improved visual tabs, Opera Neon makes surfing the web both easy and beautiful.”
Biggest miss? Hardly any plugins to play with.