The Quora Explosion (raw data)

After hearing enough mentions of Quora I went to look at it and found nothing but a sign-up page. The "about" page reads like someone tried to translate their schema into English; it tells me what the thing does but gives me no hint as to why I should care. Is there some other entrance that lets you see actual content?

Why are people using this site? How do they find out that there's something worth using inside? I only guess that they are doing so because enough people are talking about it, but I suppose that could just mean that Quora is spending a lot on PR.