Every site in the Stack Exchange network has a brief description, as in the list here - https://stackexchange.com/sites, but when you actually visit one, there's no explanation of what the site is for, unless you click through to the help, if you have already created your account on the site.
It would be nice to use the extra space in the header to show the site description, e.g. for Meta, "Q&A for meta-discussion of the Stack Exchange family of Q&A websites".
Another alternative would be to have the description in the top section of the right sidebar - some sites don't seem to have that header, so that might be a better solution.
I know it's possible to see what a site is for when you click on Ask Question, but it seems more helpful to have the description somewhere on the main page.