Sensors!

Color Light Sensor – Sparkfun
https://www.sparkfun.com/products/10656

I had a strong bias to the cheaper sensors on each site, and this is one of my favorites. I can imagine this being used as the “eyes” of a robot to identify certain objects by color. I think it would be cool to make a robot that can analyze the colors of a simple painting, drawing, or graphic and try to duplicate that coloring by having several arms that reach into pigments, mix its own shades and then draw the shapes. I also think this project could be used in a cool way to identify the color schemes of a room, someone’s outfit, or etcetera because sometimes I walk into a room that has some awesome interior decorations and I want to know the exact colors they combined so well.

Piezo Vibration Sensor – Large with Mass – Sparkfun
https://www.sparkfun.com/products/9197

The most obvious application I can think of for this would be attaching it to musical instruments to sense sound vibrations. The vibration data can then be converted into some other sensory output. Depending on how sensitive this device is, it can also be used to detect a presence through footsteps or knocking on a door. I imagine it can be applied to anything with sound, actually.

Tilt Sensor – Sparkfun
https://www.sparkfun.com/products/10313

A tilt sensor is screaming for use in an interactive piece. It could be used with a controller, lever, or a ship wheel… Anywho, the tilt sensor kind of reminds me of a project like Dave’s bubble creature. It could measure the amount of someone’s OCD in a room of tilted objects…