I'm part of a small team (usually just two people), I handle the code, he handles the graphic design. In the past I've used CVS to handle version control of the code files, and while we've included the graphics in the repository, he hasn't derived nearly as much value from it as I have.
Are there other packages that provide the better features for supporting graphics? The system would need to have an easy to use GUI interface, as I don't think it's fair to expect a graphic designer to learn command-line tools.
Additional aspect: The client software needs to run smoothly on OS X (for the designer), and Windows (for the programmer).