I agree with the tv/vcr! I took one on our 15 hr drive and it worked like a charm. Also, I bought little things for weeks before to keep them entertained. Ex:
magna doodle travel
small dry erase boards
travel size games (battleship, uno, available at Toys r Us-they have a whole section)
books on tape
a few new gameboy games
coloring books/pads/crayons
It is a LONG drive esp. with kids but, it is all worth it in the end! Good Luck!