What a coincidence...my daughter just wrote a great blog on her website about what to bring along to keep a toddler occupied on a long road trip. I don't know if you mean just in the car...but here are her suggestions.....
Ideas to Make Traveling with Toddlers a Positive Experience
Storytelling: Take turns telling getting creative with your toddler by telling stories. Trust me, your stories don’t need to be bestsellers to keep your child’s attention.
Audio Books: When you get tired of spinning your own yarns, let someone else do it for you. Check out audio books from your local library and listen to them together.
Sing: Whether you are singing alone, with your toddler, or with the radio or a CD, make music! They Might Be Giants have some fun kids’ songs that are also easy on adult ears.
Occupy their Hands: Bring along a simple activity that will require their concentration and some dexterity. Tie some loose knots in a piece of smooth rope and ask your toddler to untie the knots. Try a nuts and bolts toy (we own and enjoy this nice wooden version from Plan Toys, but as long as you are supervising you could try the real things). Bring lacing cards (here are some cute dinosaur ones; we got primary color shape lacing cards cheap from US Toy). Buy some stickers and let them stick them on the in-flight magazine or some old paper from home.
Check Out the Scenery: Don’t let the world pass you by without talking about it. Remember that every new experience builds new pathways in your little one’s brain – help make the traveling experience rich by talking about what you see outside of your window. If you can, try taking pictures of it to revisit with your toddler later, you might be surprised by how much she remembers.
Take Funny Pictures: Let your toddler get into the memory making mood by both taking funny pictures of him (at roadside attractions, in his car seat), and by letting him take pictures too. You can create a memory book later if you are so inclined.
Snacks: Don’t forget that your little one will want some healthy calories at regular intervals. Keep an assortment of portable snacks ready.
Bring Non-Toys: Most toddlers can amuse themselves for at least 15 minutes with a simple roll of blue painter’s tape or a pad of Post-it notes. What other non-toy objects might your little one be interested in?
Play Games: Play “I Spy” or the Alphabet Game (find each letter of the alphabet on signs, etc.). Make up a picture bingo game – make cards with pictures of horses, buses, stop signs, etc. and see how many your child can find.
Something New: Kids might get tired of crayons at home, but there is something magical about a new box. Bring small new toys along and open one on each travel day (or one every few hours). New stickers, new books, etc.
Light Them Up: Traveling at night? Invest a few dollars in glow in the dark bracelets, necklaces, fans, or other toys. Nothing says fun in a dark car like glowing neon chemicals! We got ours from the dollar aisle of Target, you can also find them cheap at Dollar Stores and on Amazon.
Travel-Friendly Toys: Most parents agree that toys like Etch-a-Sketch, ViewFinder, Finger/Hand Puppets, interactive books (I Spy, lift the flap)
Magnetic Puzzles/Stories: Create your own magnets using photographs or card stock. Cut them up into puzzles or let your toddler use them to make stories. (There are some more great make-your-own ideas on that link!)
Portable Activity Bags: What can you do with some pieces of yarn and a square of sandpaper? Create art! That idea and many more are on The Sunny Patch’s Activity Bags for Preschoolers page (not all travel friendly).
Take Frequent Breaks: Please don’t expect your toddler to sit for hours on end – they are used to being much more active and on the move. Plan frequent pit stops into your drive time, or let them get up and wander when possible if you’re on a plane or train. You may also want to try to schedule travel around your child’s normal nap schedule (although this may not work for some kids).