Recs.
Updated
Quora is a popular Q&A site where any questions may be asked, regardless of how subjective they may be, or what topic they may be based on.
For more on what makes Quora special, see what its users think: Quora: What makes Quora special?
Specs
Pros
Cons
Con Need to log in to see content
Quora forces people to log in to see content, which severely restricts the usefulness of the site, and limits willingness to write content for the site.
Con Forces you to use your real name
Many people are most recognisable by screen names which can't be used on Quora. It also is a matter of privacy - some people aren't comfortable having their real name listed on a website for the entire world to see.
Recommendations
Comments
Out of Date Pros + Cons
Pro Great credit system
You get credits for writing great questions and answers. This credit can later be used to promote your questions and ask knowledgeable people to answer them.