I guess this would be a “light” hack, if it’s considered a hack at all. If not, consider it an endorsement of a piece of hardware that’s handy to pair with an Ouya: the Gear Head 7-Port model UH7200 USB hub. Fits perfectly on top of the Ouya. I’ve attached mine with a couple small strips of velcro for easy removal. Handy for extra flash storage, additional controllers, etc.
Two minor drawbacks:
The open center is partially covered by the one top USB port. This unfortunately overlaps about half the power button. It’s still accessible, however. Just requires a little getting used to.
It’s no longer manufactured, and I don’t know of any other USB hub with a similar form factor. You’d have to luck out in finding one used or as a closeout. I wouldn’t mind getting a couple extras myself!