For pure organization, I found IMatch to be absolutely great. While I did switch to Lightroom last year to take advantage of the raw processing workflow, I found the management aspect of IMatch to be much better. (I had used it for 5+ years before the switch.) While it is Windows only and does use a proprietary database in the back, it's quite straightforward to export categories (basically hierarchical keywords) and custom properties into IPTC metadata. There's also a Visual Basic-based scripting engine allowing plugins, either written yourself or from other users.

A database of stolen SSNs could be perfectly open in terms of read access. So a hacker grabs a bunch of the stolen SSNs and gives one to the credit card company/bank/unemployment agency/etc. The cc company/bank/ua/etc. then checks the database to see if the number is stolen. And...they find out it is stolen and then refuse the SSN as valid.

I'm not saying it's a good idea and I also realize there are major write access issues to solve, but read access is no problem.