I realize that the above comment does not really fit within this thread, in the sense that the greyed-out "Bookmark Importer" is not a "Mac-only thing." Yet, using a Mac or not, average and power users alike are put off by the absence of this basic feature.
There is one "Mac-only thing" that I could suggest: greater integration with scholarly tools.
For instance, Mellel is one of the preferred word-processors for those who care about writing, and it is often used in conjunction with Bookends for references. It would be ideal if Opera could serve as the third element of this triad by facilitating the toggling back and forth between the browser and the word-processor, enabling for instance to select text from a website that could then be pasted in a chosen format with a short-cut. For instance, I am dealing with Chinese sources and often need to look up a particular expression in the online Buddhist Canon. Jumping from there to the word-processor, occasionally copying a passage, would be a wonderful addition.
In this business-centered world, it would be nice for Opera developers to target a slightly different niche of users, who are maybe more critical of mainstream software. Opera could market itself as the equivalent of "organic food" in the browser competition.