Q: What's the keyboard shortcut in Opera to bring up the speed dial? Speed dial actually appears on every new tab, but is there a way to open the speed dial in the active tab?
Maybe there's a chrome address for it, like about:speeddial.  

A: There definitely is something incomplete in the way Opera promotes or makes accessible all its options. If that was corrected the popularity of the browser would highly increase, i believe. Any way, back on topic, you can simply create a shortcut with the Action value: Show speed dial. Yes, that simple, > you had to try to find a similar statement in the options that pop up when you start creating your shortcut. > Note that pressing your shortcut again will toggle back to your page.
So :: Menu > Settings > Preferences (Ctrl F12) > Advanced tab > shortcuts > Edit (a copy of Opera Standard preferably) > Application > New > [choose shortcut like; f alt] > Action: Show speed dial.
I set mine at alt+f because i already had alt+d to Hide speed dial contents, wich then blanks the current tab, with an option at left bottom to show speed dial. That is useful for those few who use the great MDI feature of Opera ( + some skins have a transparent blank tab that i use as background with non-maximized pages/tab). I'm not proficient but you could also create a series and/or combination of actions with & and/or  | . The latter simply tells opera to do something else when pressing the shortcut again; you can then toggle many options.

A: I found a way to add the shortcut that brings up the speed dial on the current page!
Opera > Preferences > Advanced > Shortcuts > Keyboard Setup > Edit opera standard > Application > Edit after 9 Command click New > In Input context and short cut (left side) key 0 Command, In  Actions (right side) key/select from dropbox Show Speed dial > Click OK 
Now you can bring up speed dial in the current tab without closing the tab and reopening it! :D

A: For Mac OS:
keyboards with no home button:
fn+cmd+←
keyboards with home button:
fn+cmd+home
(Please note, depending on your settings, the function fn key may not be required.)

A: this is my solution, think it works:
Opera > Preferences > Advanced > Shortcuts > (choose field) Keyboard Setup > opera standard > Edit (two times! choose second) > (mark in tree) Application > New > (mark left side) Input [s ctrl alt] (example! my choice... choose your's!) > tab > (right side marked) Input [Go to page, "opera:speeddial"]
(brackets are not content. Just delimiters. leave out! ;) )

A: Press CTRL-T to open a new tab.  If you have Speed Dial enabled, it will appear automatically.
As per comments (thanks @barlop), I'm adding this:  There doesn't appear to be a feature to change the active window, but I did see a hint of a discussion somewhere in a restricted Google Groups page somewhere that has this as a wish-list item:  Hopefully this will change in a future version.

A: When you use speed dial on a regular basis, you know the order of the dials by heart. In this case, it is not necessary to first open the speed dial window and then select the dial. Instead, you can immediately open the desired page in the current window by pressing [Ctr+dialNumber]. For instance, if the desired page is the third dial, just press [Ctr+3].
