Another standard feature missing in Opera is word-by-word text selection in web pages.
In other browsers (Safari, Chrome, IE and Firefox), you can double-left-click on a word, hold the button and then drag. When you drag, the selection expands/contracts by each word instead of each character.
Browsers differ slightly in their implementations. For example, Chrome allows you to control whether the space after the word is selected or not. Firefox doesn't. Chrome's way is nicer.
Opera doesn't support this on web pages or rich text editors at all. But, it does work in Opera in textareas though.