Couscous is also made from rye, barley, millet, corn and acorn flour too!
I used to buy coucous made from rye from a local North African shop (in the UK). But since that shop closed I can't find any more of it, which is a shame, as I regularly cook for someone who doesn't eat wheat. But at least it's out there somewhere! So if you have any North African shops in your neighbourhood, try looking there; even if they don't stock it, they may be able to get it for you.
According to an article I just read on the web, couscous is traditionally also made from corn, millet, barley and - intriguingly - acorn flour. (Unfortunately, being new to this forum I'm not allowed to post links or direct you to other websites so I can't point you at the article!).