Zombie Ace $.99 --> Free
Pretty fun Jetpack Joyride-style game with a zombie theme. Gameplay is actually deeper than JJ with tons of upgrades, missions and landing in cities to "infect" them with zombies you've picked up.
Recommended, but be aware that upgrades in the game are pretty steep so it's either major grinding or IAPs.
Regardless, it's fun enough to play even without having your plane heavily upgraded. There's a bunch of powerups you can get in other ways (scratch cards, flying behind vehicles).
One of the better distance games I've played in a while.