I cringe when I read posts on the vacation planning boards where parents state their kids will only eat one thing or another (and whatever it is usually isn't healthy). I know some kids will get on a kick for a week or two when they really want one type of food all the time, and there is nothing wrong with serving it to them a little more often than you might otherwise (even adults get cravings after all!

). But there is something wrong with letting little Johnny only eat nuggets, ever, because "he won't eat anything else". If the kid is hungry he'll eat whatever you put in front of him. If he still refuses, fine, he doesn't have to eat it but he (or she!) gets nothing else until the next meal time (and no desert, of course). A couple of missed meals won't kill them, and it should only take a few times for them to realize it's much better to eat what Mom puts in front of them than to kick up a fuss.
My mother never made seperate meals for us once we were old enough for adult food. We ate what she cooked, period. We didn't have to clean our plates but if we didn't, no desert and no snack later on.