Opera 11 beta comes with extensions and tab stacking

                  Opera 11 beta 1 is ready for public testing.Opera 11 brings support for extension and it introduces a new feature Tab Stacking.There are already 131 extensions available for testing.
Using Tab Staking you can stack currently open tabs into one.To know about Tab Stacking follow This link

            Opera 11 also brings some new mouse gestures which were available from the time of Opera 5.Opera 11 is up to 30% faster and 30% smaller than Opera 10.63.

Opera 11 press release 

Download Opera 11 Beta