Searching for Font Audit Tools

I am looking for any suggestions on tools or methods to audit the fonts installed on my Macintosh computers. We are trying to verify licensing for all fonts and I am having trouble figuring out which fonts came with the OS (10.4), which fonts came with Adobe CS3, which fonts my users downloaded from who knows where, and which fonts we need to buy additional licensing for. I thought this would be easy but just glancing in my users fonts folders reveals over 500 fonts installed (700+ on other users). Any ideas?