This Instructable was too useful and easy not to make: Pocket Size Traveler's Dominoes.
Just print off the provided PDF and snip out all the Dominoes. I got a little fancy and did a bit of poor man's laminating: I covered the paper with clear packing tape before cutting out the individual pieces. If I had used card stock, they would have felt even more professional (though, they'd be less compact).
Here's how they came out:
The "set" fits in small plastic pill bag and is nice and portable:
Dominoes is one of those universal games that can appeal to both kids and adults. For kids, it's a great way to work on numbers, pattern matching and logic and reasoning all by playing a fun game. Here's a basic set of instructions.
This set fits well with my almost-no-supplies needed game collection. Happy playing!
Remember: there's not excuse for being bored.