I take a lot of pictures and upload them to Flickr for others to see. I always make sure to tag them with appropriate labels so that people can find more pictures of, for example Toronto or weddings. This makes finding them easier for me and for others. Google has been indexing photos and images for a few years now and has quite a collection but there's a problem of how to search for pictures using a search engine when most photos don't exactly have labels or keywords attached to them. Well, like some other interesting uses of free human potential, Google has set up a little game of sorts called the Image Labeler where you and a partner to whom you're assigned randomly see pictures flash up on the screen and type in all the label keywords you can think of appropriate to that image. When the two of you come up with a matching word, you're scored on the conciseness of that word and a new image appears. Its actually interesting to try and come up with the most accurate and descriptive words possible for high point values and at same time manage to come up with the same word as your partner did so you can score points (unmatched labels go unused). The result is that Google benefits from both additional tags to the images that you suggest for their indexing purposes and also the high likelihood that the labels assigned are accurate based on two random strangers both coming up with the same words. Go give it a try, there's a couple scoreboards to see how many points you can get compared to others.