With my most recent Amazon earnings (Thank you! Thank you to all who have purchased through one of my links!), I bought Double Shutter, a game a friend gave her daughter last year. The plan was to play with First Son so he would have a reason to use his addition facts.
He played a little but wasn't overly impressed (probably something about all those new Legos).
First Daughter, though, turns out to be a bit of a shark at the game. She beat me soundly and only needed a little help when she rolled a nine or higher.
The game is surprisingly addictive. I also think it might be a good travel game. It's not particularly small, but you play right in the tin or box so everything is contained.