WoWInterface - Special Bar for Melee Combat Skills

For starters, if this has already been done, I'd love it if you could post the link to it; I've had no luck finding anything of the sort...

I've been messing around with several melee classes (warrior, hunter, paladin) and noticed that, to some extent, they all have one or more combat skills that become active for a short time after something happens (e.g.: after a dodge, parry, citical, etc.). Invariably, I'm not fast enough on the uptake and end up losing out on the opportunity to use that move.

I figured that if there was a moveable mini action bar that could contain these special moves, and if it could be placed in some obvious spot, like the very middle of the screen, I wouldn't miss those opportunities so much (nor would others, I'd guess). Now, before you say "just get any of the action bar mods and put one in the middle of the screen," there are some conditions that should be met (if it can even be programmed this way):

Bar and icons must disappear completely if the opportunity does not exist. If an icon has disappeared, it should not be clickable.
You should be able to lock down the action bar so it's not moved around inadvertently. This could just be an extension of what Blizzard is doing with the new patch (it works really well in Gypsy).
Hotkeys should be definable for the bar, so if you see an action pop up, you can just hit a hotkey besides clicking on it with the mouse.
There should be some visual and/or sound cue that the action has activated, maybe a little flash of color around the action button?

Anyway, I'm sure there's more, but that would be a good start. Anything like that exist? If not, is it doable?