There are more and more applications that online communities build together.
First, there is Wikipedia which is a collaborative space. Even when finding a certain piece of news, you search in Google which gives you a collection of new from various media, and you should also find it in Wikipedia because anybody can modify that site and incorporate updates into it.
Also, online collaborative space is so powerful that free goodies are expanding and updating continually like Yahoo! Answers and Google Desktop Gadgets, just to name a few. I do have some contributions in Wikipedia, userscripts and Gesture Exchange. Get to learn more when there is time.