Program for image management needed

I need a recommendation for a program that allows me to select various categories for an image without moving or copying it. Example: There is a yellow car on one photo. Now I want to select "car" and "yellow things" as categories. Later the program should be able to show me all images with "yellow things" on it. An integrated rating system would also be nice. Despite the example I'm talking about managing porn, of course.

BTW, while >>3 is an interesting idea, this isn't the first time. In fact, people are constantly developing programs or filesystems that support this; they're just not aware of history.

There's a problem: metadata. Who's going to enter the metadata for several thousand images? That's right: nobody. Nobody except scientists, that is, and your software isn't going to be used by them.

My advice is to do something else. You'll just hit the same wall many of your predecessors have. Why do you think they're moving to image-based query systems like imgSeek?