At the very least you need the title and author metadata. This can be done in the filesytem, but it's unweildy. I use Fbreader and run a Calibre server to manag

At the very least you need the title and author metadata. This can be done in the filesytem, but it's unweildy. I use Fbreader and run a Calibre server to manage my collection and epub metadata. Fbreader lets me browse the filesystem, or search by different metadata.