I want to have my speed dial show an editable caption on the icon tile. Currently, I have several identical tiles for wordpress, several identical tiles for different web apps on my development site, and two identical tiles for Google docs. I'd make a more extensive speed dial if I were able to caption them, because I'd be able to put on more identical icon tiles.
Currently, I have to mouse over them to see what the title of the page is. In addition, I can rely on my memory as to which tile I'm going for by location. But the first of these two options isn't as convenient as having an editable caption, and the second is intimidating if I want to have all of my apps on there because it's a lot to remember. So I end up not putting them all on the speed dial.
This suggestion is not a deal breaker for me--I like Opera, and I've created a RegTabs folder on my bookmarks toolbar where I have this level of control. But it would be a nice feature. It would save me some clicks and some mousing.