For all those of you who have always been interested in trying Opera but never quite made the switch, perhaps it’s time to reconsider. Today the Opera team shipped version 11 beta, which adds a lot of new features to the already innovative (yet not so popular) browser including what the team says to be a revolutionary “tab stacking” functionality.

Think of tab stacking as “tab grouping” ported to the address bar: if you click and hold on a tab, you can drag it onto another one to create a “stack”, which is basically a group of tabs aimed at uncluttering your browser window. Say you want to group all your social networking sites or TSA-related links in one place, now Opera lets you do that with stacks. The implementation on OS X is nice, although I wished stacks had some sort of 3D” effect, where one would easily understand how many tabs are in each stacks. Instead, you get an expand button that indicates a tab is a stack. Animations are cool.

Opera 11 also comes with dozens of new functionalities, most of them grabbed directly from other browsers such as Chrome and Safari. Indeed, Opera users can now install browser extensions from the Extension Catalog, and it’ll be interesting to see how many developers and hackers will jump on board and release tweaks for Opera. Around 130 extensions are currently available. The new version introduces a smart address field, visual gestures, enhanced HTML5 support and overall performance improvements.

Does Opera deserve a second look? Maybe. The new features are slick and all, but I just can’t manage to stick with it as my default browser when a new version of Chrome is coming out every few weeks and Google’s browser already provides crazy speeds and thousands of addons.

Still, you can download Opera 11 Beta here and give it a try. Also watch the demo video below.