Thanks for that Albert.
I'm no expert on RDF and haven't used it yet. There are areas where this sort of thing would be very useful to me, though the designs I see don't really hack it (yet).
Examples (I've replaced angle brackets with
( and ) in the following, the CMS system kills the markup!):
Attaching a tag to a link
(a href="http://technorati.com/tag/tech" rel="tag")tech(/a)
so you've got a form of tagging within a page. (Some other people are developing a similar idea to mark up e-mail. Seems popular in some quarters, may endure.)
Attaching license details to a link
(a href="http://creativecommons.org/licenses/by/2.0/" rel="license")cc by 2.0(/a)
There has been a need for something like this for a long time. Niche market.
Embedding your address details in a page is called "hCard ". I wouldn't do that myself too many spammers.
XFN or XHTML Friends Network. When I first saw this I thought it looked nuts. Now I'm not sure.
For more information try:
http://microformats.org/
and
http://en.wikipedia.org/wiki/Microformats
While the RDF approach might be technically better I'm unconvinced that we'll see it anytime soon. There's something in RDF called RDFa, which I haven't researched.
In technical fields there's huge potential, also pricing on web pages. This could be where it really takes off. Hidden to most but vital to some. I'm sure there's write ups in that area, but I've never seen one.