I've literally just finished implementing thumbnail support in ByteHoard/e. Unlike previous versions, they're not generated on the fly, but rather whenever the file changes - the same goes for all the file metadata ByteHoard uses, like mimetypes (which now work, too) and file sizes.
As a supplement to the thumbnails, two other features have appeared. Firstly, files now have relevant icons and type descriptions, and secondly, the administrator interface has a button to entirely rescan all the files a user owns, for those cases where you've managed to confuse ByteHoard.
I've also closed a few bugs, including quota usage not changing when you delete directories, and not being able to remove administrator abilities from users.