I would LOVE to see a series or movie on just the Q Continuum; it's origin, it's purpose, how one is chosen to become a Q, and the crazy things their capabilities allow them. (I've read a couple of the ST:TNG novels where Q pull some really trippy stuff) We know that they have seen what existed before time, and what exists after it, and since they're omnipotent, you can move them all about from the far flung future back to prehistoric times. Such an endeavor would also provide plenty of plot devices to mingle with the Federation and pull off some really interesting new effects.