The CNRI Handle Space is how MIT's DSpace creates a persistant name for any object (audio, video, document, etc). It uses a bitstream type which is more specific than a MIME type (which is what is often needed).
" The Handle System, Handle Icon written in Java and available for Internet download at no cost, includes an open set of protocols, a namespace, and an implementation of the protocols." There's also a plugin for browsers. It apparently supports up to 1K resolutions per second.
DSpaces supports access control, search and retrival, and should have been available yesterday.
The specification includes an interesting use of RDF for auditing changes made to the documents: