I decided to study Yahoo! Answers (http://answers.yahoo.com/) to see if it could be a resource for library customers. It won a first place Webbie 2.0 Awards for Questions/Advice. Basically Y!A is a site where one can post his or her questions on any topic and people from around the world offer their answers/suggestions. Y!A has about 25 categories--from arts to food to history to politics to pets to business to travel.
It seems very useful. I selected a topic I've been researching and one post led me to a very relevant/helpful website. But I would only casually suggest a customer use this site--if they has time to surf the site and/or wait for answers.
When I have time, I definitely was to explore all the first place winners of the Webbie Awards.