I did this for my then 2 1/2 year old but it would work for an 8 year old too.
I picked up some disney party favor bags and put little toys in them (kinda like the sandwich bags but opaque) When she got bored or restless I pulled one out to open. I took some into the parks with me too so she would have something to do while we did kid swaps. LOL...they even worked for some other kids that were waiting for their mom and driving their poor dad nuts. I gave them one with mini bubbles and another with pipe cleaners. They were around 5 and 8 and loved them.
Some of the bags had stickers and small kids meal toys I picked up at thrift stores..
For an older child you could put in things like small puzzle books, books to read, mini video games(like the kind they give with kids meals--other option, just buy the toys and put them in), a roll of pennies to toss into the fountains at the parks, a small personal fan, an autograph book, homemade travel games like find all the license plate(I am cheap and make as much as I can to keep down costs). Basically things they can use either at the park or in the car--HECK! you could even sneak in some education in the way of geography..LOL