RFC 5988

Web Linking is RFC 5988. Via Assaf Arkin's Rounded Corners 258 I came on to an example (for Firefox and Opera) that assigns a stylesheet using .htaccess. This could also be used to turn "dumb" image files into hypermedia; a map tile JPEG could link (in its headers) to metadata, to neighboring tiles, to data for the features depicted within.

Update (2010-11-04): more from Erik Wilde.