For older kids (3+), I highly recommend the Klutz books! They kept my son occupied through most of the 14+ hour flight.
http://www.klutz.com/
For the toddler, though, you have to be creative. What worked for us on our recent flight:
1) I tore up small pieces of paper and crumpled them up into very tiny balls and had her drop them into a clear water bottle. I got her to shake the bottle (capped, of course). Then I would un-cap the bottle and she would then empty the bottle and put them in again, one by one. This was good for maybe 15 minutes.
2) I brought along some Cheerios, blueberries, grapes, etc. Using two small cups (the ones from the meal trays), I got her to transfer Cheerios, etc. from one to the other. Using the plastic utensils, she also "practiced" scooping the Cheerios. A bit messy, but it kept her occupied. :)
Good luck. You both will do fine.