Handle them like a good steak: quick, high heat and do not cook past medium rare. (With lamb, this isn't just a matter of taste -- it will toughen quickly if overcooked.) A rib chop (looks like a mini-T bone steak) should be fairly tender on its own. Other lamb chops benefit from marinade. You might want to moderate the temperature down somewhat depending on thickness so it doesn't get way overcooked on the outside while still being beyond rare in the middle. I almost always grill lamb chops.
Thanks for the reminder, we should have some at a good price soon. Yum!