Moga Pro Power Game Controller
Moga is a well-known company that makes gamepads and game controllers for mobile devices, but the new Moga Pro Power is the best yet. Offering a Game Controller that docks your Nexus 5, and will even charge it while you play those fun battery-draining games like Asphalt 8: Airborne. The Moga Power Pro features a built-in 2,200 mAh battery that will charge your Nexus 5 to nearly full, all while you're gaming.
$79 from Moga