It's a statisics site with everything under the sun. Pick a category from the drop menu, then sub-category, click GO and get the stats. Why am I posting this under Internet Marketing? Because these stats in related categories to your site(s) can help with things like "who to target", "what to provide", etc. Just play around with it and you find many ways it can help you with marketing your site.
Well, I like the site. But I donno how accurate they are. Anyway, nice one. I stumbled it too.
Your right about accuracy. It does state sources and the year(s). I found a lot fom 2004 for example, but it should still be accurate enough to get some benefit out of it.