hard to do when google lists webpages that are just word listings a aardvark aback abacus abaft abalone /etc.
This is possibly suited to a post about toolbar feedback but, I ran an experiment a while back doing such a thing with a bunch of students from a uni. We came up with a phrase that produced no results. We then set a Google alert monitoring the phrase. We then used the phrase in a couple of sites - one brand new, no links and no doubt sandboxed. We also used the phrase in an esatblished site. Before we added the phrase to the body we added it to the titles, description and meta tags etc. No result after several days. But when we added it to the body of the sandboxed site it came through as an alert with a matter of 48 hours or so. However, if you searched for the name of the site [again semi-unique] via the main search results then no result. So, the moral of this story, Google will supply a Google alert for something it tells you that is not in its index!