Crowdsourcing, basically means to use others in order to accomplish a goal, usually the other people get rewarded somehow. click here for a more detailed explanation
I found a pretty cool site simalir to Google Image Labeler that basically makes research a game. You and a partner play a bunch of games that will actually send data from your game to the creator to enhance how search engines work and other data.
For example you're playing a word guessing game with a friend, you have to get your friend to guess the word by describing it.
You: emotion felt between two people
You: roses and hearts
Ding ding ding you win!
That data for both sides gets used to make search engines understand how humans think, making our results more relevant, for example, if you search for an emotion felt between two people, you may get the result love.
then if you search for roses and hearts, you may also get love.
Now for images, you and a partner are shown the same image, you both have to describe the image in detail, avoiding the words that each-other would use. Every unique word you guess you gain points, if you say the same common keywords you both move on to the next image.
This improves search because for example, computers have a hard time interpreting images, unlike humans, thus a human can make out detail in pictures and label that image. This makes searching for images retrieve so much more relevant results.
Anywho the site I discovered today is Gwap.com they have a bunch of games that are basically research games, they use players answers and questions to make search engines more powerful.
I gotta say most of the games are actually quite fun you should try em out, and you'll be contributing to world search engines!