Are you into photography? Do you have a camera with manual settings? If not, here you can try out what it is like to use those manual settings to generate different looks with shutter speed and aperture, oh and what is ISO again? All this can be easily tested and tried on this website.
Oh, and for all the people already owning a DSLR or similar camera: this can help you understand some things about the settings you can use and what they actually do.