My own approach, if you're interested, is to treat the filesystem as a repository of bytestreams, loosely organised by YYYY folders and then a single level below that, A-Z. I then read everything into a database, deduplicating by file hash and have a 3NF-modelled metadata layer (with 6NF history tables based on the anchor modelling concept) in Postgresql, also with a Django front-end. Only the file hash is stored in the database, not the binary blob. I keep things in sync using Dropbox's delta API.

Or at least, that's the plan. I've only implemented it as far as photo storage is concerned. Haven't yet figured out if Dropbox can be part of the general solution - security and privacy concerns.