Opera 11 Beta has two very interesting features. One is a native Click To Flash-like feature that allows a plug-ins to be engaged only on demand. I’m not sure that this feature alone would be enough to try out Opera since FireFox as well as Safari has Click To Flash. The second feature is worth a look though.
Tab Stacking is a really nifty idea. We all use multiple tabs and wouldn’t it be nice to group some of these tabs together? Sure you can bookmark the tabs and then open them all at once. But what if you wanted to group them to open up more space for other tabs? You can stack the tabs or expand them. Elegant.