XFN - XHTML Friends Network [via]:

XFN puts a human face on linking. As more people have come online and begun to form social networks, services such as Technorati and Feedster have arisen in an attempt to show how the various nodes are connected. Such services are useful for discovering the mechanical connections between nodes, but they do not uncover the human relationships between the people responsible for the nodes. […]

The links in Joe’s blogroll would look something like this:

<a href="http://jane-blog.example.org/"
rel="sweetheart date met">Jane</a>

<a href="http://dave-blog.example.org/"
rel="friend met">Dave</a>

<a href="http://darryl-blog.example.org/"
rel="friend met">Darryl</a>

<a href="http://www.metafilter.com/"
>MetaFilter</a>

<a href="http://james-blog.example.com/"
rel="met">James Expert</a>

This is so simple, I can’t imagine any reason not to use it.

It is also possible to use advanced CSS2 to insert content before or after elements. This can be used to recreate the practice of “starring” links to people physically met as follows:

a[rel~="met"]:after {content: " *";}

FAQ:

Tools, Sites, Spiders etc. that use or support XFN will be added to this page.

Yeah, that’s an empty list right there. But, once again, it’s so simple — why not be one of the first to use it? Here’s the list of possible values (which can all be combined) :

• met

• contact / acquaintance / friend

• co-worker / colleague

• co-resident / neighbor

• child / parent / sibling / spouse / kin

• muse / crush / date / sweetheart

• me

Notes: the difference between “co-worker” and “colleague” (which may be obvious to the English-speaking, but not to me) is that a colleague is someone who works in the same field as you do (shouldn’t there be something for students in the same class, by the way?); “me” denotes your own web presence, obviously; and there is no mention of accepting “neighbour.”