Is there a standardized (meta?) tag for the date of a website?

Question

One thing that search engines really suck with is the date when a website was created. You know the problem: You search for some CSS or JavaScript problem and Google returns

Answer 1

I suppose the DC.date tag could be used for that. The Dublin Core metadata is relatively established and well known.

You could also mark your websites with XMDP, which has a date tag that is supposed to be the date of the last modification.