Ideas for entertaining kids on a long car trip?

My kids are 4 and 16 months. We have an 8 hour drive to New Hampshire at the end of July...I'm hoping to borrow or buy a portable DVD player, but I'm looking for other ideas to keep them occupied and not completely drive me insane on the way. I think my 4 year old will be fine with the magna doodle, books, coloring...it's my 1 year old that I'm most worried about. Any good ideas will be appreciated. (It will probably be just me and them in the car as my husband is driving some of his youth group kids in the other car, he's a youth pastor...we're hoping to talk one of the youth kids into riding with me to help me out though)