Following lines, detecting colors, responding to light. It is still far from "seeing", but the LEGO Mindstorms EV3 & NXT sensors could be very useful when used properly.
Category Mindstorms Sensors
LEGO Mindstorms EV3 and NXT include many sensors. Use of the sensors is what makes the robot powerfull.
With the use of ultrasound the LEGO Mindstorms EV3 & NXT Ultrasonic sensors could detect the distance to an object. You can use it in many different ways most of them very interesting and fun. Some of them a little more challenging, but rewarding.
Do you know you can detect how many degrees has the motor rotated? All you have to do is the Rotation sensor of LEGO Mindstorms EV3 & NXT. It is a sensor embedded in the motors themselves.
Touched, Released, Bumped. These are the basic three states of the LEGO Mindstorms touch sensors both in EV3 and NXT versions of the robots.
There are common patterns when working with LEGO Mindstorms Sensors that could be applied to Sound, Rotation, Gyro, Color and all the other sensors.