Very few rel values are included in the current IANA link registry: http://www.iana.org/assignments/link-relations/link-relations.xhtml For values defined in a RFC or de-facto standard values (like "service"), the registry is useful but I'm afraid that if we turn it into a Wiki it might get really messy with dozens of rel values, and people relying on these values for semantics when another choice might be more appropriate (a controlled vocabulary for example).
We might want to separate rel values used in webpages ( http://www.w3.org/TR/xhtml-modularization/abstraction.html#s_common_attrtypes) from those used in Atom feeds too. Hadrien
