Among the other "20 percent time" projects that NY Times's tech columnist David Pogue highlights is a somewhat trivial but interesting Google Sets.
...type in several items in a series (like “cleveland browns” and “dallas cowboys”); Google fleshes out the list with others like it (all the other football teams). Great when something’s on the tip of your tongue (a kind of fruit, president, car, holiday, currency) but can remember only something like it.
These are nice conveniences on the Internet that let you find you what you want based on correlated things. You can now even search an image with a correlated image or identify a song by humming a few lines on your mobile.