A number of these messages have ROS stacks dedicated to manipulating them.
More information on how to use the sensor_msgs/LaserScan message can be found in the laser_pipeline stack.
More information on how to use the sensor_msgs/Image and sensor_msgs/CameraInfo messages can be found in the image_pipeline stack.
The sensor_msgs/JointState message is published by joint_state_controller, and received by robot_state_publisher (which combines the joint information with urdf to publish a robot's tf tree).
The sensor_filters package provides easy-to-setup nodes and nodelets for running filters on the sensor data.