--This piece from FamilyFun has a number of tips, including dressing kids for comfort and packing an extra outfit in the carry-on, even if your child seems to be past the having-accidents stage. If you have a long delay, something spills or someone is, er, sick, you'll be glad you had the clean clothes. If it's a night flight, it's fun to pack pajamas so the kids can try to sleep.

--From personal experience, I'd add: If your child is in diapers, carry on at least one for every hour of the flight. And then one more.

--Here's the Transportation Security Administration's official primer on flying with children, which has vital information on how to handle formula, food and medication on the plane.

--And here's the Federal Aviation Administration site, which is the place to find out about safety seat regulations. It strongly encourages you to use a child-safety seat or other approved safety device for kids up to 40 pounds (after that, they can use a seat belt). Yes, it does involve buying a ticket for the child.

--Portable DVD players can make a long flight a lot easier. If you have two children, invest in the kind that allows you to hook up two sets of headphones. Just make sure you charge the player's battery, and check that it's working, before you fly.

--Take lots of books (think slim and flexible, so you can fit more in your carry-on), coloring books, plain paper, and crayons. Take as many as you think you'll need, then add a few more. In my experience, you need to change things up more frequently than you think. If space is tight, pack a Magna-Doodle, which provides hours of cheap drawing fun with no mess. And the pen is attached.

--Don't take small toys, irreplaceable toys, or toys with lots of pieces. They're bound to fall on the floor or get lodged between the seats and get lost. And if the irreplaceable stuffed animal is left behind, it could ruin your whole trip. 

--This site has tips from a flight attendant, including one I second: have everyone in your party use the bathroom right before you fly -- and between connections -- whether they have to go or not. It seems lately that the seat-belt sign stays on constantly when you're flying, and kids may have a very hard time waiting for the end of a flight to use the bathroom.

--If you need to buy water after you get through security to have for kids to drink as you're taking off and landing (helps ease ear pain), pack little paper cups from home so you won't have to buy several pricey bottles. Moms who are breastfeeding can discreetly nurse during those parts of the flight. For older kids, gum helps the ears.

--Flying with autistic children can be especially challenging. This USA Today story has tips on that, which include preparing your child beforehand by showing him pictures of the airplane, the terminal at the airport, and the destination. The story also recommends preparing the flight attendants by telling them as you board that your child is autistic and may have special needs. You might be allowed to board early, which may be less overwhleming for your child.

Here's more from the TSA on traveling with children with disabilities.