You can use them like potatoes. We made a load of soup when we grew them, which was lovely. We also had them peeled and roasted. But we stopped growing them because they create a lot of hot air, IYKWIM!
We grow and sometimes eat jerusalem artichokes and find that if you change the water at least once during the cooking phase it cuts down dramatically with the wind (that is of course if you are either boiling or steaming them). Our boys are not too fussed on them so we don't have them too often.
One of the first things my dad said about them was Fartichokes... I'm not sure if I was that keen that I'd grow them given the truth behind what they're nicknamed
like that name Cassiepod. The good think about them is that they will grow very well, pretty much anywhere. We mostly use them as animal feed - the goats eat the tops (which look a bit like sunflowers) and they love them and then the pigs and put in to eat the roots. Very versatile for that purpose. The main thing to remember when planting them is that once they are planted then they will always be there. They grow from the tiniest root piece so best to choose a permanent area. They are very hardy - our winter went down to -18 this (opps! last year) and we left them in the ground over winter and they were still good when we dug some up in the spring.