I thought it was just a hearsay until i saw it at the neopets website. Just keep on refreshing the page until the google ad displays. Take a look at the source code and you will see the google_hint option on google ad script. it looked something like this:
google_hints = "microsoft instant messenger pizza hut virgin mobile doughnut disney world fruit snacks";
Definitely its going to help you display targeted ads to your site specially if its not displaying any relevant ads. The only problem i could see here is that it might be abused just like what happened to the meta keywords which was called keyword stuffing . The main reason why the search engines are nowadays ignoring them. However, you will need to contact google before you can use the code. I dont really know the process and i haven't tested it yet. Total number of characters on google_hints should not exceed by 1024 characters.
