KongZhong Corp.'s (KONG) second-quarter earnings climbed 70% as the Chinese mobile entertainment company lowered product-development costs and more than doubled revenue in its relatively new Internet game segment.

For more than a year, KongZhong--which offers instant-messaging services, games and content for wireless devices in China--has been enhancing the gaming side of its business. Last year, it bought Dacheng Networks, a developer of 3D online role-playing games. ...