Audion is a cool little player, however there are no controller apps for it, well not that I've seen, and I check VersionTracker daily.
But, Audion does have the neat ability of being able to remain in the background even if you click it's buttons. So, what I've done is found a nice little skin that makes Audion fit snugly in the corner of my screen, where I can often see it while I have other apps open. Then, I can click it's buttons in the background, and it stays there, without having to be brought to the front.
-Ryan