As of WP3.3, adding/editing Quicktags is no longer a simple matter. And I've always modified my toolbar to simplify my editing, adding buttons for "center" and non-breaking spaces. For this, JayJ works great.
But I also need quicktag buttons that prompt for parameters then adds those switches to the tag (for instance, an FLV button that prompts for video size and thumbnail image.)
The ability to sort and even remove/hide existing unnecessary tags would also be great.