Raw

Ok, Cool URIs don't change, 'nuff said. But given that, there's scope for fun. Not sure when, but at some point in the past few years I got pulled from the opaque=make-it-illegible gang to opaque=make it pretty & poke-aroundable posse. But anyhow, coincidentally Wrox have a snippet from the forthcoming (this month) Professional Web 2.0 Programming on their site : Future-Proofing Your URIs by Erik Bruchez; there's now a site devoted to "beautiful" URIs : welldesignedurls.org and there's a Draft TAG Finding - The use of Metadata in URIs (seems sensible, though I'd have probably put the fourth conclusion first).

See also : URI Templating, the Spec

Oh yeah, and the hash/slash for identifying things permathread has regenerated post-303 finding. 

See also : thing-described-by.org