DH and I love to use it as the greens in a salad. If you are used to lettuce in a salad, it has a much stronger flavor that takes some getting used to, but we really enjoyed it (we made a mixed green salad from chard, kale, mustard and collard greens). Alternately, chard is wonderful used in place of spinach in recipes. I.e., any recipe that calls for cooked spinach, just substitute the chard. Wilt/cook it in the same way and you'll hardly know the difference. For that of course you only want to use the green leaves - not the stems.
Chickens do love it too and it is great for producing lovely orange, healthy yokes. I usually try to plant enough for the family AND the chickens.