Stop screaming at your kids! Road trip clips: One clip for each kid. If they are sweet, clip stays up, if they are not, clip comes down. Everyone with a clip on the visor gets a treat at the next stop :-) love this idea! OR Field Trip Clip.
The Fun Cheap or Free Queen: How to survive a road trip with two babies by yourself.roadtrip tricks, tips, and creative ideas! (plus link within the site to more tips from a trip w/ slightly older kids)
10 ways to keep kids happy in the car on a road trip. A couple of these were new to me--like having your kid color a paper car and moving it along a ribbon strung up in the car to visually show your progress along your route.