I agree that a great place to start is looking at things your kids love to "eat out," then make a healthier version at home.
If they love chicken nuggets, for example, buy chicken tenders, cut into bite-sized pieces, coat in beaten eggs, then dip into your favorite coating (I like a combination of flour, corn meal, and wheat germ) and bake.
If they love pizza, make homemade pizza with whole wheat crust, or use this recipe:
http://stickafork.net/2012/04/16/cauliflower-crust-pizza/
to get some more veggies in them.
If they like burgers, try putting some zucchini into a food processor and mixing it with the ground beef, eggs, and spices, to make a tender and healthier version.
If they like mac n cheese, make your own sauce by heating milk over med-low heat and slowly adding shredded cheese until it melts into the milk (stirring slowly but constantly with a whisk). Then pour the sauce over some whole wheat elbow mac, top with shredded cheese and bread crumbs and bake for 20-minutes or so until the top is golden and bubbly. For bonus points, you can run some steamed cauliflower through a food processor, and mix it into the sauce.
If you just start out with making the standards, better, you'll increase your confidence and feel like you're putting something a little better out there.