Picture Optimization

I have noticed that pictures that have proper titles and links are giving about 15% of all target traffic that comes to one of my site. Did anybody tried to do the same? I mean get target traffic by optimizing pictures?

Usually I give a name that corresponds to general site title and specific item of pic. For instance in the site is about cars and there is a Lamborghini Diablo on a picture, I’d call it lamborghini_diablo_cars.jpg, or cars_lamborghini_diablo.jpg – depending on which keyword it must be stressed.

What do you think about optimization of pictures? Do you use pictures optimization on your sites?