The ragebar is the search field in the header of every page on this site. Press the magnifier, top right, and start typing.
It searches the corpus live as you type — no page reload — and the engine rages while it retrieves: the meter under the field is driven by your actual typing speed and by how many results come back. When the corpus returns nothing, it turns red and says so.
Results come from this site’s own index, the same one behind ?s=rage. Retrieval first, generation second — that is what the R and the G in RAGE are for.