Maya*Made has a great photo tutorial showing you how to make this travel pillow that is perfect for long car and airplane rides or sending along to camp or visits with grandma. It even has a little pocket for special friends or secret notes!
A photo scavenger hunt is a wonderful idea for a child that isn't reading yet; making it a seasonal scavenger hunt puts it into the brilliant category! The post says she will email the PDF above to anyone interested but that was a year ago so I'm not sure if it's still available but it wouldn't hurt to ask with a pretty please and a cherry on top! All the details and brilliance at Wee Life!
MayaMade shares this great and simple pattern for sleeping masks! Perfect to encourage naps during car trips. She also made some terrific customized travel bags for each of the kids so be sure to check out all the details :)
*Edited to add: The car in the picture is not moving; when driving, the seat belts should always go over the child's shoulder.*
Chasing Cheerios has come up with a dozen activity bags for her toddler to use during a trip! She gives all the details here. As great as these are for traveling these would be wonderful to keep stashed somewhere and bring out whenever the need strikes :)