meta-tags tutorials?

I went in search of tutorials on meta-tags and
got mired in a load of seemingly old information.
Any suggestions on recently updated, high quality
tutorials?
________
Background to question..
While a few pages I was looking at suggested
meta-tags were becoming less important, there
are various things I would like to express within
my web pages that seem well suited to such tags,
including (but not limited to..).

Title, author, description, keywords *, document
creation date, document _updated_ date (as
opposed to 'last date _uploaded_'), page rating
(some pages not recommended for kiddies
w/out adult supervision)..

* again, there were recent suggestions that
search engines mow completely ignore the much
abused 'keywords' tag, but I will continue
to include them in the hope the s.e.'s can
devise an algortihm to sort the dross.

--
Andrew Thompson
* http://www.PhySci.org/ PhySci software suite
* http://www.1point1C.org/ 1.1C - Superluminal!
* http://www.AThompson.info/andrew/ personal site