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.

I'm working on something like this, but I can't make any promises on when will I finish it. With a series of PHP scripts, and assuming you work in the command line in either Windows or Linux, you will be able to classify any file with any tags in a text-based database (ok for up to 100000 files/database). Text-based = good, portable, non-tied to a particular tool or system, processable with Perl, PHP, etc., editable by hand, all software works on it, easy backups, easy repairs, easy everything, simple. KISS.

Fields are dynamic and regex-based. You can do stuff like "this file is type=Car-Racing;rating=5", or "Give me files of type=Car-.* and files rating=[0-3]". Naturally, you're returned a list of file names, so you can do anything useful with it. Examples: Reclassify them. Browse them with your favorite tool. Hardlink them to a temporary directory so you can browse it with ACDSee and use Back and Forwards with the results of your query. Copy them to a friend. Etc.

Like I said it's all command-line based, thus fast and useful. It's all PHP (not through a web server), so it runs on pretty much everything.

I might later make a Windows GUI client to query the database, and/or a web interface.