Hi LXE, welcome to SoR.
You can use the LEDs for light sensing, but you have to connect them reversed. Clear LEDs give good results to day light, colored LEDs are sensitive to their color. This is a method some people use to determine the color of an object. I don't remember exactly the schematic, but if you can't find it through Google, I'm sure another SoR member will point you in the right direction.
Nice board you have there. I see it already has a light sensor, and the built in LEDs you can't use for this purpose. If you want a cool idea, how about this:
- use a TV remote to control the board
- use the LEDs to display a Knight Rider
- use the speaker to play the music of the KR movie
- display some text on the LCD, some phrase Kit was usually saying