Managing ROM sets

So I've been asking around the emulation community how they organize their ROM sets. I don't like the idea of ALL games together and like to separate them by region. So, for example, my NES roms are all good dumps and for the most part no revisions. They are in folders US, Europe, Japan, Unlicensed, and Hacks. It makes finding them easier when looking for a specific game. I only have a handful of out of US games anyway but my US set is complete.

How do you guys do it?