Obviously, asking for AdSense to let us tell them what keywords apply to our site would be too prone to abuse, but what about this: a tag that says "Instead of using the context of just this page, show ads for the context of my site as a whole."
The reason I think this would be good is that I have a FAQ page for my site that shows really inappropriate ads because of a line that says something like "beware of 'business opportunity' scams on the Internet." Because of that, all the ads on the page are for business opportunities. Yikes!
However, if I put up a brand new page on the site, ads appropriate to the theme of the site come up. If there was some way I could have a tag in the AdSense code that says, "use site-wide context," I wouldn't have this problem, and Google could still serve ads related to my site in general.
Does that make sense? Does anyone else think it would be a good idea? Does anyone think Google would go for it? :-)
(While I'm asking for the moon, it would also be nifty if I could look through ads and have an "Inappropriate" link to click to teach AdSense what *kinds* of ads weren't cool. But I think this is a little out of the realm of what they'll do. :-))