like the title says, I've found the following making my life much easier comparing to any other major browsers, so I really wish the they can be included again in new Opera.
- switch most recently visited tabs by hitting Ctrl+Tab, which also show all opened tabs in front so you can jump around (now Ctrl+F1 does it but this combination is hard to reach, physical distance on keyboard I mean)
or enable customisable keyboard shortcut to let users do whatever they like??
- access (first nine) speed dial links by shortcut Ctrl+# .
- bring bookmark back with a quick access by hitting F4 (none of current extensions serves this, and I generally don't like extensions), as well as OperaLink.
- right-click and "Block content" (again, if there's an extension, I'd prefer built-in function..)
- able to keep multiple Tab-less windows.
- confirm exit... (I've heard it's on Mac but I use windows)
(finally, I don't know how hard it is, but I wish Linux version would come soon.)